4-(p-QUINONYL)-2-HYDROXYBUTANAMIDE DERIVATIVES FOR TREATMENT OF MITOCHONDRIAL DISEASES

ABSTRACT

Methods of treating or suppressing mitochondrial diseases, such as Friedreich&#39;s ataxia (FRDA), Leber&#39;s Hereditary Optic Neuropathy (LHON), mitochondrial myopathy, encephalopathy, lactacidosis, and stroke (MELAS), Kearns-Sayre Syndrome (KSS), are disclosed, as well as compounds useful in the methods of the invention, such as 4-(p-quinolyl)-2-hydroxybutanamide derivatives. Methods and compounds useful in treating other disorders such as amyotrophic lateral sclerosis (ALS), Huntington&#39;s disease, Parkinson&#39;s disease, and pervasive developmental disorders such as autism are also disclosed. Energy biomarkers useful in assessing the metabolic state of a subject and the efficacy of treatment are also disclosed. Methods of modulating, normalizing, or enhancing energy biomarkers, as well as compounds useful for such methods, are also disclosed.

CROSS-REFERENCE TO RELATED APPLICATIONS

This patent application claims priority benefit of U.S. Provisional Patent Application No. 61/002,126 filed on Nov. 6, 2007 and of U.S. Provisional Patent Application No. 61/002,127, filed on Nov. 6, 2007. The entire contents of those patent applications are hereby incorporated by reference herein.

TECHNICAL FIELD

The application discloses compositions and methods useful for treatment, prevention, or suppression of diseases, developmental delays and symptoms related to mitochondrial disorders, such as Friedreich's Ataxia, Leber's Hereditary Optic Neuropathy, Kearns-Sayre Syndrome, mitochondrial myopathy, encephalopathy, lactacidosis, and stroke, and cerebral vascular accidents, and for modulating energy biomarkers in a subject. Compositions of the present invention are administered to a subject for the purpose of compensating for mitochondrial dysfunction and for improving mitochondrial functions. Methods and compounds useful in treating other disorders such as Amyotrophic Lateral Sclerosis (ALS), Huntington's and Parkinson's are also disclosed.

BACKGROUND

Mitochondria are organelles in eukaryotic cells, popularly referred to as the “powerhouse” of the cell. One of their primary functions is oxidative phosphorylation. The molecule adenosine triphosphate (ATP) functions as an energy “currency” or energy carrier in the cell, and eukaryotic cells derive the majority of their ATP from biochemical processes carried out by mitochondria. These biochemical processes include the citric acid cycle (the tricarboxylic acid cycle, or Kreb's cycle), which generates reduced nicotinamide adenine dinucleotide (NADH+H⁺) from oxidized nicotinamide adenine dinucleotide (NAD⁺), and oxidative phosphorylation, during which NADH+H⁺ is oxidized back to NAD⁺. (The citric acid cycle also reduces flavin adenine dinucleotide, or FAD, to FADH₂; FADH₂ also participates in oxidative phosphorylation.)

The electrons released by oxidation of NADH+H⁺ are shuttled down a series of protein complexes (Complex I, Complex II, Complex III, and Complex IV) known as the respiratory chain. These complexes are embedded in the inner membrane of the mitochondrion. Complex IV, at the end of the chain, transfers the electrons to oxygen, which is reduced to water. The energy released as these electrons traverse the complexes is used to generate a proton gradient across the inner membrane of the mitochondrion, which creates an electrochemical potential across the inner membrane. Another protein complex, Complex V (which is not directly associated with Complexes I, II, III and IV) uses the energy stored by the electrochemical gradient to convert ADP into ATP.

The citric acid cycle and oxidative phosphorylation are preceded by glycolysis, in which a molecule of glucose is broken down into two molecules of pyruvate, with net generation of two molecules of ATP per molecule of glucose. The pyruvate molecules then enter the mitochondria, where they are completely oxidized to CO₂ and H₂O via oxidative phosphorylation (the overall process is known as aerobic respiration). The complete oxidation of the two pyruvate molecules to carbon dioxide and water yields about at least 28-29 molecules of ATP, in addition to the 2 molecules of ATP generated by transforming glucose into two pyruvate molecules. If oxygen is not available, the pyruvate molecule does not enter the mitochondria, but rather is converted to lactate, in the process of anaerobic respiration.

The overall net yield per molecule of glucose is thus approximately at least 30-31 ATP molecules. ATP is used to power, directly or indirectly, almost every other biochemical reaction in the cell. Thus, the extra (approximately) at least 28 or 29 molecules of ATP contributed by oxidative phosphorylation during aerobic respiration are critical to the proper functioning of the cell. Lack of oxygen prevents aerobic respiration and will result in eventual death of almost all aerobic organisms; a few organisms, such as yeast, are able to survive using either aerobic or anaerobic respiration.

When cells in an organism are temporarily deprived of oxygen, anaerobic respiration is utilized until oxygen again becomes available or the cell dies. The pyruvate generated during glycolysis is converted to lactate during anaerobic respiration. The buildup of lactic acid is believed to be responsible for muscle fatigue during intense periods of activity, when oxygen cannot be supplied to the muscle cells. When oxygen again becomes available, the lactate is converted back into pyruvate for use in oxidative phosphorylation.

Mitochondrial dysfunction contributes to various disease states. Some mitochondrial diseases are due to mutations or deletions in the mitochondrial genome. If a threshold proportion of mitochondria in the cell is defective, and if a threshold proportion of such cells within a tissue have defective mitochondria, symptoms of tissue or organ dysfunction can result. Practically any tissue can be affected, and a large variety of symptoms may be present, depending on the extent to which different tissues are involved.

One such disease is Friedreich's ataxia (FRDA or FA). Friedreich's ataxia is an autosomal recessive neurodegenerative and cardiodegenerative disorder caused by decreased levels of the protein frataxin. Frataxin is important for the assembly of iron-sulfur clusters in mitochondrial respiratory-chain complexes. Estimates of the prevalence of FRDA in the United States range from 1 in every 22,000-29,000 people (see www.nlm.nih.gov/medlineplus/ency/article/001411.htm) to 1 in 50,000 people (see www.umc-cares.org/health_info/ADAM/Articles/001411.asp). The disease causes the progressive loss of voluntary motor coordination (ataxia) and cardiac complications. Symptoms typically begin in childhood, and the disease progressively worsens as the patient grows older; patients eventually become wheelchair-bound due to motor disabilities.

Another disease linked to mitochondrial dysfunction is Leber's Hereditary Optic Neuropathy (LHON). The disease is characterized by blindness which occurs on average between 27 and 34 years of age; blindness can develop in both eyes simultaneously, or sequentially (one eye will develop blindness, followed by the other eye two months later on average). Other symptoms may also occur, such as cardiac abnormalities and neurological complications.

Yet another devastating syndrome resulting from mitochondrial defects is mitochondrial myopathy, encephalopathy, lactacidosis, and stroke (MELAS). The disease can manifest itself in infants, children, or young adults. Strokes, accompanied by vomiting and seizures, are one of the most serious symptoms; it is postulated that the metabolic impairment of mitochondria in certain areas of the brain is responsible for cell death and neurological lesions, rather than the impairment of blood flow as occurs in ischemic stroke. Other severe complications, including neurological symptoms, are often present, and elevated levels of lactic acid in the blood occur.

Another mitochondrial disease is Kearns-Sayre Syndrome (KSS). KSS is characterized by a triad of features including: (1) typical onset in persons younger than age 20 years; (2) chronic, progressive, external ophthalmoplegia; and (3) pigmentary degeneration of the retina. In addition, KSS may include cardiac conduction defects, cerebellar ataxia, and raised cerebrospinal fluid (CSF) protein levels (e.g., >100 mg/dL). Additional features associated with KSS may include myopathy, dystonia, endocrine abnormalities (e.g., diabetes, growth retardation or short stature, and hypoparathyroidism), bilateral sensorineural deafness, dementia, cataracts, and proximal renal tubular acidosis. Thus, KSS may affect many organ systems.

Co-Enzyme Q10 Deficiency is a respiratory chain disorder, with syndromes such as myopathy with exercise intolerance and recurrent myoglobin in the urine manifested by ataxia, seizures or mental retardation and leading to renal failure (Di Mauro et al., (2005) Neuromusc. Disord., 15:311-315), childhood-onset cerebellar ataxia and cerebellar atrophy (Masumeci et al., (2001) Neurology 56:849-855 and Lamperti et al., (2003) 60:1206:1208); and infantile encephalomyopathy associated with nephrosis. Biochemical measurement of muscle homogenates of patients with CoQ10 deficiency showed severely decreased activities of respiratory chain complexes I and II+III, while complex IV (COX) was moderately decreased (Gempel et al., (2007) Brain, 130(8):2037-2044).

Complex I Deficiency or NADH dehydrogenase NADH-CoQ reductase deficiency is a respiratory chain disorder, with symptoms classified by three major forms: (1) fatal infantile multisystem disorder, characterized by developmental delay, muscle weakness, heart disease, congenital lactic acidosis, and respiratory failure; (2) myopathy beginning in childhood or in adult life, manifesting as exercise intolerance or weakness; and (3) mitochondrial encephalomyopathy (including MELAS), which may begin in childhood or adult life and consists of variable combinations of symptoms and signs, including ophthalmoplegia, seizures, dementia, ataxia, pigmentary retinopathy, sensory neuropathy, and uncontrollable movements.

Complex II Deficiency or Succinate dehydrogenase deficiency is a respiratory chain disorder with symptoms including encephalomyopathy and various manifestations, including failure to thrive, developmental delay, hyoptonia, lethargy, respiratory failure, ataxia, myoclonus and lactic acidosis.

Complex III Deficiency or Ubiquinone-cytochrome C oxidoreductase deficiency is a respiratory chain disorder with symptoms categorized in four major forms: (1) fatal infantile encephalomyopathy, congenital lactic acidosis, hypotonia, dystrophic posturing, seizures, and coma; (2) encephalomyopathies of later onset (childhood to adult life): various combinations of weakness, short stature, ataxia, dementia, sensory neuropathy, pigmentary retinopathy, and pyramidal signs; (3) myopathy, with exercise intolerance evolving into fixed weakness; and (4) infantile histiocytoid cardiomyopathy.

Complex IV Deficiency or Cytochrome C oxidase deficiency is a respiratory chain disorder with symptoms categorized in two major forms: (1) encephalomyopathy, which is typically normal for the first 6 to 12 months of life and then show developmental regression, ataxia, lactic acidosis, optic atrophy, ophthalmoplegia, nystagmus, dystonia, pyramidal signs, respiratory problems and frequent seizures; and (2) myopathy with two main variants: (a) Fatal infantile myopathy-may begin soon after birth and accompanied by hypotonia, weakness, lactic acidosis, ragged-red fibers, respiratory failure, and kidney problems: and (b) Benign infantile myopathy—may begin soon after birth and accompanied by hypotonia, weakness, lactic acidosis, ragged-red fibers, respiratory problems, but (if the child survives) followed by spontaneous improvement.

Complex V Deficiency or ATP synthase deficiency is a respiratory chain disorder including symptoms such as slow, progressive myopathy.

CPEO or Chronic Progressive External Ophthalmoplegia Syndrome is a respiratory chain disorder including symptoms such as visual myopathy, retinitis pigmentosa, or dysfunction of the central nervous system.

In addition to congenital disorders involving inherited defective mitochondria, acquired mitochondrial dysfunction contributes to diseases, particularly neurodegenerative disorders associated with aging like Parkinson's, Alzheimer's, and Huntington's Diseases. The incidence of somatic mutations in mitochondrial DNA rises exponentially with age; diminished respiratory chain activity is found universally in aging people. Mitochondrial dysfunction is also implicated in excitoxic, neuronal injury, cerebral vascular accidents such as that associated with seizures, stroke and ischemia.

The diseases above appear to be caused by defects in complex I of the respiratory chain. Electron transfer from complex Ito the remainder of the respiratory chain is mediated by the compound coenzyme Q (also known as ubiquinone). Oxidized coenzyme Q (CoQ^(ox) or ubiquinone) is reduced by complex Ito reduced coenzyme Q (CoQ^(red) or ubiquinol). The reduced coenzyme Q then transfers its electrons to complex III of the respiratory chain (skipping over complex II), where it is re-oxidized to CoQ^(ox) (ubiquinone). CoQ^(ox) can then participate in further iterations of electron transfer.

Very few treatments are available for patients suffering from these diseases. Recently, the compound idebenone has been proposed for treatment of Friedreich's ataxia. While the clinical effects of idebenone have been relatively modest, the complications of mitochondrial diseases can be so severe that even marginally useful therapies are preferable to the untreated course of the disease. Another compound, MitoQ, has been proposed for treating mitochondrial disorders (see U.S. Pat. No. 7,179,928); clinical results for MitoQ have not yet been reported. Administration of coenzyme Q10 (CoQ10) and vitamin supplements have shown only transient beneficial effects in individual cases of KSS.

Mitochondrial dysfunction has also been implicated in various other diseases. Recent studies have suggested that as many 20 percent of patients with autism have markers for mitochondrial disease (Shoffner, J. the 60^(th) Annual American Academy of Neurology meeting in Chicago, April 12-19, (2008); Poling, J S et al J. child Neurol. 2008, 21(2) 170-2; and Rossignol et al., Am. J. Biochem. & Biotech. (2008) 4, 208-217). Some cases of autism have been associated with several different organic conditions, including bioenergetic metabolism deficiency suggested by the detection of high lactate levels in some patients (Coleman M. et al, Autism and Lactic Acidosis, J. Autism Dev Disord., (1985) 15: 1-8; Laszlo et al Serum serotonin, lactate and pyruvate levels in infantile autistic children, Clin. Chim. Acta (1994) 229:205-207; and Chugani et al., Evidence of altered energy metabolism in autistic children, Progr. Neuropsychopharmacol Biol Psychiat., (1999) 23:635-641) and by nuclear magnetic resonance imagining as well as positron emission tomography scanning which documented abnormalities in brain metabolism. Although the mechanism of hyperlactacidemia remains unknown, a likely possibility involves mitochondrial oxidative phosphorylation dysfunction in neuronal cells. A small subset of autistic patients diagnosed with deficiencies in complex I or III of the respiratory chain have been reported in the literature (see Oliveira, G., Developmental Medicine & Child Neurology (2005) 47 185-189; and Filipek, P A et al., Journal of Autism and Developmental Disorders (2004) 34:615-623). However, in many of the cases of autism where there is some evidence of mitochondrial dysfunction, there is an absence of the classic features associated with mitochondrial disease, such as mitochondrial pathology in muscle biopsy (see Rossignol, D. A. et al., Am J. Biochem. & Biotech, (2008) 4 (2) 208-217).

Recently, Hayashi et al. (Science Express, published online 3 Apr. 2008: DOI: 10.1126/science.1156906, and Ishikawa et al., Science (2 May 2008) 320 (5876) 661-664) indicated that mitochondrial DNA mutations can contribute to tumor progression by enhancing the metastatic potential of tumor cells.

The ability to adjust biological production of energy has applications beyond the diseases described above. Various other disorders can result in suboptimal levels of energy biomarkers (sometimes also referred to as indicators of energetic function), such as ATP levels. Treatments for these disorders are also needed, in order to modulate one or more energy biomarkers to improve the health of the patient. In other applications, it can be desirable to modulate certain energy biomarkers away from their normal values in an individual that is not suffering from disease. For example, if an individual is undergoing an extremely strenuous undertaking, it can be desirable to raise the level of ATP in that individual.

Accordingly, compounds for treatment of mitochondrial disease and/or to adjust biological production of energy have a wide range of practical applications.

DISCLOSURE OF THE INVENTION

In one embodiment, the invention embraces compounds of formula I:

where R is selected from the group consisting of:

where the * indicates the point of attachment of R to the remainder of the molecule;

-   R¹, R², and R³ are independently selected from hydrogen,     C₁-C₆-alkyl, and O—C₁-C₆-alkyl; -   R⁴ is C₁-C₆-alkyl; -   R⁵ and R⁶ are independently selected from hydrogen, hydroxy, alkoxy,     C₁-C₄₀-alkyl, C₁-C₄₀-alkenyl, C₁-C₄₀-alkynyl, and aryl; where the     alkyl, alkenyl, alkynyl, or arylgroups may optionally be substituted     with     -   —OR¹⁰, —S(O)₀₋₂R¹⁰, —CN, —F, —Cl, —Br, —I, —NR¹⁰R^(10′), oxo,         C₃-C₆-cycloalkyl, aryl, aryl-C₁-C₆-alkyl, heteroaryl,         heterocyclyl, —C(O)—R¹¹, —C(O)—C₀-C₆-alkyl-aryl, —C(O)—O—R¹¹,         —C(O)—O—C₀-C₆-alkyl-aryl, —C(O)—N—R¹¹R^(11′),         —C(O)—N—C₀-C₆-alkyl-aryl, —N—C(O)—R¹¹, —N—C(O)—C₀-C₆-alkyl-aryl;         where the aryl, heteroaryl and heterocyclyl ring substituents         may be further substituted with C₁-C₆-alkyl, C₁-C₆-haloalkyl,         oxo, hydroxy, C₁-C₆-alkoxy, —C(O)—C₁-C₆-alkyl and         —C(O)—O—C₁-C₆-alkyl; and where one of the carbons of the alkyl,         alkenyl, or alkynyl groups may be substituted with a heteroatom         selected from O, N or; or -   R⁵ and R⁶ together with the atom to which they are attached form a     saturated or unsaturated 3-8 membered ring, optionally incorporating     one or more additional, such as one, two, or three, N, O, or S atoms     and optionally substituted with oxo, —OR¹⁰, —SR¹⁰, —CN, —F, —Cl,     —Br, —I, —NR¹⁰R^(10′), C₁-C₆-alkyl, C₁-C₆-haloalkyl;     hydroxy-C₁-C₆-alkyl, —C(O)—H, —C(O)—C₁-C₆-alkyl, —C(O)-aryl,     —C(O)—OH, or —C(O)—O—C₁-C₆-alkyl; or -   R⁵ and R⁶ together with the nitrogen atom to which they are attached     form a N,N′-disubstituted piperazine where the nitrogen substitution     at the 4-position is a group identical to the substitution at the     1-position forming a compound of formula I-Saa or I-Sbb, where R¹,     R², R³, and R⁴ are as defined above:

-   R¹⁰ and R^(10′) are independently selected from the group consisting     of H, C₁-C₆-alkyl, C₁-C₆-haloalkyl, aryl, aryl-C₁-C₆-alkyl,     heteroaryl, heterocyclyl, —C(O)—H, —C(O)—C₁-C₆-alkyl, —C(O)-aryl and     —C(O)—C₁-C₆-alkyl-aryl; -   R¹¹ and R^(11′) are selected from hydrogen and C₁-C₆-alkyl; and -   M and M′ are independently selected from hydrogen, —C(O)—R¹²,     —C(O)—C₁-C₆-alkenyl, —C(O)—C₁-C₆-alkynyl, —C(O)-aryl;     —C(O)-heteroaryl, —C(O)O—R¹², —C(O)NR¹²R¹², —SO₂OR¹²,     —SO₂—C₁-C₆-alkyl, —SO₂-haloC₁-C₆-alkyl; —SO₂-aryl, —SO₂—NR¹²R¹²,     —P(O)(OR¹²)(OR¹²), and C-linked mono or di-peptide, where R¹² is     hydrogen or C₁-C₆-alkyl optionally substituted with —OH, —NH₂,     —NH(C₁-C₄alkyl), —N(C₁-C₄alkyl)₂, —C(O)—OH, —C(O)—O—C₁-C₄-alkyl or     halogen; -   with the proviso that the compound is not     N-(6-amino-3-methyl-2,4-dioxo-1-phenyl-1,2,3,4-tetrahydropyrimidin-5-yl)-2-hydroxy-2-methyl-4-(2,4,5-trimethyl-3,6-dioxocyclohexa-1,4-dienyl)butanamide     or     N-(6-amino-3-methyl-2,4-dioxo-1-phenyl-1,2,3,4-tetrahydropyrimidin-5-yl)-4-(2,5-dihydroxy-3,4,6-trimethylphenyl)-2-hydroxy-2-methylbutanamide;     and all salts, stereoisomers, mixtures of stereoisomers, prodrugs,     metabolites, solvates, and hydrates thereof.

In another embodiment, the invention embraces a method of treating or suppressing a mitochondrial disorder, modulating one or more energy biomarkers, normalizing one or more energy biomarkers, or enhancing one or more energy biomarkers, by administering a therapeutically effective amount or effective amount of one or more compounds of formula I-S as described above.

In one embodiment, the invention embraces compounds of formula I:

where R is selected from the group consisting of:

where the * indicates the point of attachment of R to the remainder of the molecule;

-   R¹, R², and R³ are independently selected from hydrogen and     C₁-C₆-alkyl; -   R⁴ is C₁-C₆-alkyl; -   R⁵ and R⁶ are independently selected from hydrogen, hydroxy, alkoxy,     C₁-C₄₀-alkyl, C₁-C₄₀-alkenyl, C₁-C₄₀-alkynyl, and aryl; where the     alkyl, alkenyl, alkynyl, or arylgroups may optionally be substituted     with     -   —OR¹⁰, —S(O)₀₋₂R¹⁰, —CN, —F, —Cl, —Br, —I, —NR¹⁰R^(10′), oxo,         C₃-C₆-cycloalkyl, aryl, aryl-C₁-C₆-alkyl, heteroaryl,         heterocyclyl, —C(O)—R¹¹, —C(O)—C₀-C₆-alkyl-aryl, —C(O)—O—R¹¹,         —C(O)—O—C₀-C₆-alkyl-aryl, —C(O)—N—R¹¹R^(11′),         —C(O)—N—C₀-C₆-alkyl-aryl, —N—C(O)—R¹¹, —N—C(O)—C₀-C₆-alkyl-aryl;         where the aryl, heteroaryl and heterocyclyl ring substituents         may be further substituted with C₁-C₆-alkyl, C₁-C₆-haloalkyl,         oxo, hydroxy, C₁-C₆-alkoxy, —C(O)—C₁-C₆-alkyl and         —C(O)—O—C₁-C₆-alkyl; and where one of the carbons of the alkyl,         alkenyl, or alkynyl groups may be substituted with a heteroatom         selected from O, N or; or -   R⁵ and R⁶ together with the atom to which they are attached form a     saturated or unsaturated 3-8 membered ring, optionally incorporating     one or more additional, such as one, two, or three, N, O, or S atoms     and optionally substituted with oxo, —OR¹⁰, —SR¹⁰, —CN, —F, —Cl,     —Br, —I, —NR¹⁰R^(10′), C₁-C₆-alkyl, C₁-C₆-haloalkyl;     hydroxy-C₁-C₆-alkyl, —C(O)—H, —C(O)—C₁-C₆-alkyl, —C(O)-aryl,     —C(O)—OH, or —C(O)—O—C₁-C₆-alkyl; or -   R⁵ and R⁶ together with the nitrogen atom to which they are attached     form a N,N′-disubstituted piperazine where the nitrogen substitution     at the 4-position is a group identical to the substitution at the     1-position forming a compound of formula Iaa or Ibb, where R¹, R²,     R³, and R⁴ are as defined above:

-   R¹⁰ and R^(10′) are independently selected from the group consisting     of H, C₁-C₆-alkyl, C₁-C₆-haloalkyl, aryl, aryl-C₁-C₆-alkyl,     heteroaryl, heterocyclyl, —C(O)—H, —C(O)—C₁-C₆-alkyl, —C(O)-aryl and     —C(O)—C₁-C₆-alkyl-aryl; -   R¹¹ and R^(11′) are selected from hydrogen and C₁-C₆-alkyl; and -   M and M′ are independently selected from hydrogen, —C(O)—R¹²,     —C(O)—C₁-C₆-alkenyl, —C(O)—C₁-C₆-alkynyl, —C(O)-aryl;     —C(O)-heteroaryl, —C(O)O—R¹², —C(O)NR¹²R¹², —SO₂OR¹²,     —SO₂—C₁-C₆-alkyl, —SO₂-haloC₁-C₆-alkyl; —SO₂-aryl, —SO₂—NR¹²R¹²,     —P(O)(OR¹²)(OR¹²), and C-linked mono or di-peptide, where R¹² is     hydrogen or C₁-C₆-alkyl optionally substituted with —OH, —NH₂,     —NH(C₁-C₄alkyl), —N(C₁-C₄alkyl)₂, —C(O)—OH, —C(O)—O—C₁-C₄-alkyl or     halogen; -   with the proviso that the compound is not     N-(6-amino-3-methyl-2,4-dioxo-1-phenyl-1,2,3,4-tetrahydropyrimidin-5-yl)-2-hydroxy-2-methyl-4-(2,4,5-trimethyl-3,6-dioxocyclohexa-1,4-dienyl)butanamide     or     N-(6-amino-3-methyl-2,4-dioxo-1-phenyl-1,2,3,4-tetrahydropyrimidin-5-yl)-4-(2,5-dihydroxy-3,4,6-trimethylphenyl)-2-hydroxy-2-methylbutanamide;     and all salts, stereoisomers, mixtures of stereoisomers, prodrugs,     metabolites, solvates, and hydrates thereof.

In another embodiment, the invention embraces a method of treating or suppressing a mitochondrial disorder, modulating one or more energy biomarkers, normalizing one or more energy biomarkers, or enhancing one or more energy biomarkers, by administering a therapeutically effective amount or effective amount of one or more compounds of formula I as described above.

In another embodiment, the invention embraces compounds of formula Ia:

-   R¹, R², and R³ are independently selected from hydrogen and     C₁-C₆-alkyl; -   R⁴ is C₁-C₆-alkyl; -   R⁵ and R⁶ are independently selected from hydrogen, hydroxy, alkoxy,     C₁-C₄₀-alkyl, C₁-C₄₀-alkenyl, C₁-C₄₀-alkynyl, and aryl; where the     alkyl, alkenyl, alkynyl or aryl groups may optionally be substituted     with     -   —OR¹⁰, —S(O)₀₋₂R¹⁰, —CN, —F, —Cl, —Br, —I, —NR¹⁰R^(10′), oxo,         C₃-C₆-cycloalkyl, aryl, aryl-C₁-C₆-alkyl, heteroaryl,         heterocyclyl, —C(O)—R¹¹, —C(O)—C₀-C₆-alkyl-aryl, —C(O)—O—R¹¹,         —C(O)—O—C₀-C₆-alkyl-aryl, —C(O)—N—R¹¹R¹¹,         —C(O)—N—C₀-C₆-alkyl-aryl, —N—C(O)—R¹¹, —N—C(O)—C₀-C₆-alkyl-aryl;         where the aryl, heteroaryl and heterocyclyl ring substituents         may be further substituted with C₁-C₆-alkyl, C₁-C₆-haloalkyl,         oxo, hydroxy, C₁-C₆-alkoxy, —C(O)—C₁-C₆-alkyl and         —C(O)—O—C₁-C₆-alkyl; and where one of the carbons of the alkyl,         alkenyl, or alkynyl groups may be substituted with a heteroatom         selected from O, N or S; or -   R⁵ and R⁶ together with the atom to which they are attached form a     saturated or unsaturated 3-8 membered ring, optionally incorporating     one or more additional, such as one, two, or three, N, O, or S     atoms, optionally substituted with oxo, —OR¹⁰, —SR¹⁰, —CN, —F, —Cl,     —Br, —I, —NR¹⁰R^(10′), C₁-C₆-alkyl, C₁-C₆-haloalkyl;     hydroxy-C₁-C₆-alkyl, —C(O)—H, —C(O)—C₁-C₆-alkyl , —C(O)-aryl,     —C(O)—OH, or —C(O)—O—C₁-C₆-alkyl; or -   R⁵ and R⁶ together with the nitrogen atom to which they are attached     form a N,N′-disubstituted piperazine where the nitrogen substitution     at the 4-position is a group identical to the substitution at the     1-position forming a compound of formula Iaa, where R¹, R², R³, and     R⁴ are as defined above:

-   R¹⁰ and R^(10′) are independently selected from the group consisting     of hydrogen, C₁-C₆-alkyl, C₁-C₆-haloalkyl, aryl, aryl-C₁-C₆-alkyl,     heteroaryl, heterocyclyl, —C(O)—H, —C(O)—C₁-C₆-alkyl, —C(O)-aryl and     —C(O)—C₁-C₆-alkyl-aryl; and -   R¹¹ and R^(11′) are selected from hydrogen and C₁-C₆-alkyl; with the     proviso that the compound is not     N-(6-amino-3-methyl-2,4-dioxo-1-phenyl-1,2,3,4-tetrahydropyrimidin-5-yl)-2-hydroxy-2-methyl-4-(2,4,5-trimethyl-3,6-dioxocyclohexa-1,4-dienyl)butanamide;     and all salts, stereoisomers, mixtures of stereoisomers, prodrugs,     metabolites, solvates, and hydrates thereof.

In another embodiment, the invention embraces compounds of formula Ia, where R¹, R², and R³ are selected from methyl, ethyl, n-propyl, isopropyl, cyclopropyl, n-butyl, isobutyl, sec-butyl, t-butyl, cyclobutyl, cyclopropyl-methyl, methyl-cyclopropyl, pentyl where the point of attachment of the pentyl group to the remainder of the molecule can be at any location on the pentyl fragment, cyclopentyl, hexyl where the point of attachment of the hexyl group to the remainder of the molecule can be at any location on the hexyl fragment, and cyclohexyl; and all salts, stereoisomers, mixtures of stereoisomers, prodrugs, metabolites, solvates, and hydrates thereof.

In another embodiment, the invention embraces compounds of formula Ia, where one of the R¹, R², and R³ groups is methyl, and the remaining groups are hydrogen. In another embodiment the invention embraces compounds of formula Ia, where two of the R¹, R², and R³ groups are methyl, and the remaining group is hydrogen. In another embodiment the invention embraces compounds of formula Ia, where R¹, R², and R³ are methyl; and all salts, stereoisomers, mixtures of stereoisomers, prodrugs, metabolites, solvates, and hydrates thereof.

In another embodiment, the invention embraces compounds of formula Ia, where R⁴ is selected from methyl, ethyl, n-propyl, i-propyl, or cyclopropyl; and in another embodiment R⁴ is methyl, and all salts stereoisomers, mixtures of stereoisomers, prodrugs, metabolites, solvates, and hydrates thereof.

In another embodiment, the invention embraces compounds of formula Ia, where R¹, R², R^(3′) and R⁴ are methyl; and all salts stereoisomers, mixtures of stereoisomers, prodrugs, metabolites, solvates, and hydrates thereof.

In another embodiment, the invention embraces compounds of formula Ia, where R⁵ and R⁶, are independently selected from hydrogen, and C₁-C₆ alkyl optionally substituted with hydroxy, alkoxy or —C(O)O—C₁-C₆ alkyl, and all salts stereoisomers, mixtures of stereoisomers, prodrugs, metabolites, solvates, and hydrates thereof.

In another embodiment, the invention embraces compounds of formula Ia, where R⁵ and R⁶ are independently hydrogen or C₁-C₆ alkyl optionally substituted with aryl; and a salt, a stereoisomer, or a mixture of stereoisomers thereof. In another embodiment, one of R⁵ and R⁶ is hydrogen and the other is C₁-C₆ alkyl optionally substituted with aryl; and a salt, a stereoisomer, or a mixture of stereoisomers thereof. In another embodiment, R⁵ and R⁶ are hydrogen; and a salt, a stereoisomer, or a mixture of stereoisomers thereof.

In another embodiment, the invention embraces compounds of formula Ia, where R⁵ is hydrogen and R⁶ is unsubstituted C₁-C₆ alkyl; and in another embodiment R⁶ is selected from methyl, ethyl, propyl, isopropyl, butyl, isobutyl, 2-methylbutyl, and cyclopropyl; and all salts stereoisomers, mixtures of stereoisomers, prodrugs, metabolites, solvates, and hydrates thereof.

In another embodiment, the invention embraces compounds of formula Ia, where R⁵ is hydrogen and R⁶ is C₁-C₆ alkyl substituted with hydroxy, alkoxy or —C(O)O—-C₁-C₆ alkyl; and all salts, stereoisomers, mixtures of stereoisomers, prodrugs, metabolites, solvates, and hydrates thereof. In another embodiment, the invention embraces compounds of formula Ia, where R⁵ is hydrogen and R⁶ is C₁-C₆ alkyl substituted with hydroxy, and all salts, stereoisomers, mixtures of stereoisomers, prodrugs, metabolites, solvates, and hydrates thereof. In another embodiment, the invention embraces compounds of formula Ia, where R⁵ is hydrogen and R⁶ is selected from —(CH₂)₁₋₆—OH; 1-hydroxyprop-2-yl and 2-hydroxyprop-1-yl; and all salts, stereoisomers, mixtures of stereoisomers, prodrugs, metabolites, solvates, and hydrates thereof.

In another embodiment, the invention embraces compounds of formula Ia, where R⁵ and R⁶ are independently selected from C₁-C₆ alkyl substituted with hydroxyl; for example R⁵ and R⁶ are substituted with hydroxyethyl; and all salts, stereoisomers, mixtures of stereoisomers, prodrugs, metabolites, solvates, and hydrates thereof.

In another embodiment, the invention embraces compounds of formula Ia, where R⁵ is hydrogen and R⁶ is independently selected from C₁-C₆ alkyl substituted with —NR¹⁰R^(10′), where R¹⁰ and R^(10′) are independently selected from the group consisting of hydrogen, C₁-C₆-alkyl, C₁-C₆-haloalkyl, aryl, aryl-C₁-C₆-alkyl, heteroaryl, heterocyclyl, —C(O)—H, —C(O)—C₁-C₆-alkyl, —C(O)-aryl and —C(O)—C₁-C₆-alkyl-aryl; and all salts, stereoisomers, mixtures of stereoisomers, prodrugs, metabolites, solvates, and hydrates thereof. In another embodiment, the invention embraces compounds of formula Ia, where R⁵ is hydrogen and R⁶ is independently selected from C₁-C₆ alkyl substituted with —NH₂, —NH(C₁-C₆-alkyl), or —N(C₁-C₆-alkyl)₂, for example where R⁶ is dimethylaminoalkyl; and all salts, stereoisomers, mixtures of stereoisomers, prodrugs, metabolites, solvates, and hydrates thereof. In another embodiment, the invention embraces pharmaceutically acceptable salts of compounds of formula Ia, where R⁵ is hydrogen and R⁶ is dimethylaminoethyl; for example hydrochloride or mesylate salts.

In another embodiment, the invention embraces compounds of formula Ia, where R⁵ is hydrogen and R⁶ is C₁-C₆ alkyl optionally substituted with phenyl, for example benzyl or phenylethyl, and all salts, stereoisomers, mixtures of stereoisomers, prodrugs, metabolites, solvates, and hydrates thereof.

In another embodiment, the invention embraces compounds of formula Ia, where R⁵ is hydrogen and R⁶ is C₁-C₆ alkyl optionally substituted with heterocyclyl or heteroaryl; and all salts, stereoisomers, mixtures of stereoisomers, prodrugs, metabolites, solvates, and hydrates thereof.

In another embodiment, the invention embraces compounds of formula Ia, where R⁵ is hydrogen and R⁶ is C₁-C₆ alkyl optionally substituted with a nitrogen containing heterocyclyl and all salts, stereoisomers, mixtures of stereoisomers, prodrugs, metabolites, solvates, and hydrates thereof. In another embodiment the invention embraces compounds of formula Ia, where R⁵ is hydrogen and R⁶ is C₁-C₆ alkyl optionally substituted with pyrrolidinyl, piperidinyl, piperazinyl, or morpholinyl, and all salts, stereoisomers, mixtures of stereoisomers, prodrugs, metabolites, solvates, and hydrates thereof.

In another embodiment, the invention embraces compounds of formula Ia, where R⁵ is hydrogen and R⁶ is C₁-C₆ alkyl optionally substituted with a nitrogen containing heteroaryl, for example imidazolyl, pyridinyl, pyrrolyl, and pyrimidinyl, and all salts, stereoisomers, mixtures of stereoisomers, prodrugs, metabolites, solvates, and hydrates thereof. In another embodiment, the invention embraces compounds of formula Ia, where R⁵ is hydrogen and R⁶ is C₁-C₆ alkyl optionally substituted with a nitrogen containing heteroaryl, for example imidazol-1-yl or pyridin-2-yl and all salts, stereoisomers, mixtures of stereoisomers, prodrugs, metabolites, solvates, and hydrates thereof. In another embodiment, the invention embraces compounds of formula Ia, where R⁵ is hydrogen and R⁶ is 3-(1H-imidazol-1-yl)propyl, pyridin-2-ylmethyl, or 2-(pyridin-2-yl)ethyl, and all salts, stereoisomers, mixtures of stereoisomers, prodrugs, metabolites, solvates, and hydrates thereof.

In another embodiment, the invention embraces compounds of formula Ia, where R⁵ is hydrogen and R⁶ is C₁-C₆ alkyl optionally substituted with an oxygen or sulfur containing heterocyclyl or heteroaryl, for example tetrahydropyranyl, tetrahydrofuranyl, tetrahydrothienyl, pyranyl, furanyl, thienyl, benzopyranyl, or benzofuranyl; and all salts, stereoisomers, mixtures of stereoisomers, prodrugs, metabolites, solvates, and hydrates thereof.

In another embodiment, the invention embraces compounds of formula Ia, where R⁵ and R⁶ together with the nitrogen atom to which they are attached form an optionally substituted 3 to 8-membered nitrogen containing heterocyclyl ring, for example an azetidine, a pyrrolidine, a piperidine, a piperazine, a morpholine or an azepane ring; and all salts, stereoisomers, mixtures of stereoisomers, prodrugs, metabolites, solvates, and hydrates thereof.

In another embodiment, the invention embraces compounds of formula Ia, where R⁵ and R⁶ together with the nitrogen atom to which they are attached form piperidin-1-yl, 4-hydroxy-piperidin-1-yl, 4-methyl-piperazin-1-yl, 4-benzyl-piperazin-1-yl, and azepan-1-yl and all salts, stereoisomers, mixtures of stereoisomers, prodrugs, metabolites, solvates, and hydrates thereof.

In another embodiment, the invention embraces compounds of formula Ia, where R⁵ and R⁶ together with the nitrogen atom to which they are attached form a N,N′-disubstituted piperazine where the nitrogen substitution at the 4-position is a group identical to the substitution at the 1-position forming a compound of formula Iaa, where R¹, R², R³, and R⁴ are as defined above:

and all salts, stereoisomers, mixtures of stereoisomers, prodrugs, metabolites, solvates, and hydrates thereof.

In another embodiment, the invention embraces compounds of the formula Ib:

-   R¹, R², and R³ are independently selected from hydrogen and     C₁-C₆-alkyl; -   R⁴ is C₁-C₆-alkyl; -   R⁵ and R⁶ are independently selected from hydrogen, hydroxy, alkoxy,     C₁-C₄₀-alkyl, C₁-C₄₀-alkenyl, C₁-C₄₀-alkynyl, or aryl; where the     alkyl, alkenyl, alkynyl, or aryl groups may optionally be     substituted with -   —OR¹⁰, —S(O)₀₋₂R¹⁰, —CN, —F, —Cl, —Br, —I, —NR¹⁰R^(10′), oxo,     C₃-C₆-cycloalkyl, aryl, aryl-C₁-C₆-alkyl, heteroaryl, heterocyclyl,     —C(O)—R¹¹, —C(O)—C₀-C₆-alkyl-aryl, —C(O)—O—R¹¹,     —C(O)—O—C₀-C₆-alkyl-aryl, —C(O)—N—R¹¹R¹¹, —C(O)—N—C₀-C₆-alkyl-aryl,     —N—C(O)—R¹¹, —N—C(O)—C₀-C₆-alkyl-aryl; where the aryl, heteroaryl     and heterocyclyl ring substituents may be further substituted with     C₁-C₆-alkyl, C₁-C₆-haloalkyl, oxo, hydroxy, C₁-C₆-alkoxy,     —C(O)—C₁-C₆-alkyl and —C(O)—O—C₁-C₆-alkyl; and where one of the     carbons of the alkyl, alkenyl, or alkynyl groups may be substituted     with a heteroatom selected from O, N or S; and where -   R⁵ and R⁶ together with the atom to which they are attached form a     saturated or unsaturated 3-8 membered ring, optionally incorporating     one or more additional, such as one, two, or three, N, O, or S     atoms, optionally substituted with oxo, —OR¹⁰, —SR¹⁰, —CN, —F, —Cl,     —Br, —I, —NR¹⁰R^(10′), C₁-C₆-alkyl, C₁-C₆-haloalkyl;     hydroxy-C₁-C₆-alkyl, —C(O)—H, —C(O)—C₁-C₆-alkyl, —C(O)-aryl,     —C(O)—OH, or —C(O)—O—C₁-C₆-alkyl; or -   R⁵ and R⁶ together with the nitrogen atom to which they are attached     form a N,N′-disubstituted piperazine where the nitrogen substitution     at the 4-position is a group identical to the substitution at the     1-position forming a compound of formula Ibb, where R¹, R², R³, and     R⁴ are as defined above:

-   R¹⁰ and R^(10′) are independently selected from the group consisting     of hydrogen, C₁-C₆-alkyl, C₁-C₆-haloalkyl, aryl, aryl-C₁-C₆-alkyl,     heteroaryl, heterocyclyl, —C(O)—H, —C(O)—C₁-C₆-alkyl, —C(O)-aryl and     —C(O)—C₁-C₆-alkyl-aryl; -   R¹¹ and R^(11′) are selected from hydrogen and C₁-C₆-alkyl; -   M and M′ are independently selected from hydrogen, —C(O)—R¹²,     —C(O)—C₁-C₆-alkenyl, —C(O)—C₁-C₆-alkynyl, —C(O)-aryl;     —C(O)-heteroaryl, —C(O)O—R¹², —C(O)NR¹²R¹², —SO₂OR¹²,     —SO₂—C₁-C₆-alkyl, —SO₂-haloC₁-C₆-alkyl; —SO₂-aryl, —SO₂—NR¹²R¹²,     —P(O)(OR¹²)(OR¹²), and C-linked mono- or di-peptide, where R¹² is     hydrogen or C₁-C₆-alkyl optionally substituted with —OH, —NH₂,     —NH(C₁-C₄alkyl), —N(C₁-C₄alkyl)₂, —C(O)—OH, —C(O)—O—C₁-C₄-alkyl or     halogen; and all salts, stereoisomers, mixtures of stereoisomers,     prodrugs, metabolites, solvates, and hydrates thereof.

In another embodiment, the invention embraces compounds of formula Ib, where R¹, R², and R³ are selected from methyl, ethyl, n-propyl, isopropyl, cyclopropyl, n-butyl, isobutyl, sec-butyl, t-butyl, cyclobutyl, cyclopropyl-methyl, methyl-cyclopropyl, pentyl where the point of attachment of the pentyl group to the remainder of the molecule can be at any location on the pentyl fragment, cyclopentyl, hexyl where the point of attachment of the hexyl group to the remainder of the molecule can be at any location on the hexyl fragment and cyclohexyl; and all salts, stereoisomers, mixtures of stereoisomers, prodrugs, metabolites, solvates, and hydrates thereof.

In another embodiment, the invention embraces compounds of formula Ib, where one of the R¹, R², and R³ groups is methyl, and the remaining groups are hydrogen. In another embodiment the invention embraces compounds of formula Ib, where two of the R¹, R², and R³ groups are methyl, and the remaining group is hydrogen. In another embodiment the invention embraces compounds of formula Ib, where R¹, R², and R³ are methyl; and all salts, stereoisomers, mixtures of stereoisomers, prodrugs, metabolites, solvates, and hydrates thereof.

In another embodiment, the invention embraces compounds of formula Ib, where R⁴ is selected from methyl, ethyl, n-propyl, i-propyl, or cyclopropyl; and in another embodiment R⁴ is methyl, and all salts stereoisomers, mixtures of stereoisomers, prodrugs, metabolites, solvates, and hydrates thereof.

In another embodiment, the invention embraces compounds of formula Ib, where R¹, R², R^(3′) and R⁴ are methyl; and all salts stereoisomers, mixtures of stereoisomers, prodrugs, metabolites, solvates, and hydrates thereof.

In another embodiment, the invention embraces compounds of formula Ib, where R⁵ and R⁶, are independently selected from hydrogen, and C₁-C₆ alkyl optionally substituted with hydroxy, alkoxy or —C(O)O—C₁-C₆ alkyl, and all salts stereoisomers, mixtures of stereoisomers, prodrugs, metabolites, solvates, and hydrates thereof.

In another embodiment, the invention embraces compounds of formula Ib, where R⁵ and R⁶ are independently hydrogen or C₁-C₆ alkyl optionally substituted with aryl; and a salt, a stereoisomer, or a mixture of stereoisomers thereof. In another embodiment, one of R⁵ and R⁶ is hydrogen and the other is C₁-C₆ alkyl optionally substituted with aryl; and a salt, a stereoisomer, or a mixture of stereoisomers thereof. In another embodiment, R⁵ and R⁶ are hydrogen; and a salt, a stereoisomer, or a mixture of stereoisomers thereof.

In another embodiment, the invention embraces compounds of formula Ib, where R⁵ is hydrogen and R⁶ is unsubstituted C₁-C₆ alkyl, and in another embodiment R⁶ is selected from methyl, ethyl, propyl, isopropyl, butyl, isobutyl, 2-methylbutyl, cyclopropyl and all salts stereoisomers, mixtures of stereoisomers, prodrugs, metabolites, solvates, and hydrates thereof.

In another embodiment, the invention embraces compounds of formula Ib, where R⁵ is hydrogen and R⁶ is C₁-C₆ alkyl substituted with hydroxy, alkoxy or —C(O)O—C₁-C₆ alkyl; and all salts, stereoisomers, mixtures of stereoisomers, prodrugs, metabolites, solvates, and hydrates thereof. In another embodiment, the invention embraces compounds of formula Ib, where R⁵ is hydrogen and R⁶ is C₁-C₆ alkyl substituted with hydroxy, and all salts, stereoisomers, mixtures of stereoisomers, prodrugs, metabolites, solvates, and hydrates thereof. In another embodiment, the invention embraces compounds of formula Ib, where R⁵ is hydrogen and R⁶ is selected from —(CH₂)₁₋₆—OH; 1-hydroxyprop-2-yl and 2-hydroxyprop-1-yl; and all salts, stereoisomers, mixtures of stereoisomers, prodrugs, metabolites, solvates, and hydrates thereof.

In another embodiment, the invention embraces compounds of formula Ib, where R⁵ and R⁶ are independently selected from C₁-C₆ alkyl substituted with hydroxyl; for example R⁵ and R⁶ are substituted with hydroxyethyl; and all salts, stereoisomers, mixtures of stereoisomers, prodrugs, metabolites, solvates, and hydrates thereof.

In another embodiment, the invention embraces compounds of formula Ib, where R⁵ is hydrogen and R⁶ is independently selected from C₁-C₆ alkyl substituted with —NR¹⁰R^(10′), where R¹⁰ and R^(10′) are independently selected from the group consisting of hydrogen, C₁-C₆-alkyl, C₁-C₆-haloalkyl, aryl, aryl-C₁-C₆-alkyl, heteroaryl, heterocyclyl, —C(O)—H, —C(O)—C₁-C₆-alkyl, —C(O)-aryl and —C(O)—C₁-C₆-alkyl-aryl; and all salts, stereoisomers, mixtures of stereoisomers, prodrugs, metabolites, solvates, and hydrates thereof.

In another embodiment, the invention embraces compounds of formula Ib where R⁵ is hydrogen and R⁶ is independently selected from C₁-C₆ alkyl substituted with —NH₂, —NH(C₁-C₆-alkyl), or —N(C₁-C₆-alkyl)₂, for example where R⁶ is dimethylaminoalkyl such as dimethylaminoethyl; and all salts, stereoisomers, mixtures of stereoisomers, prodrugs, metabolites, solvates, and hydrates thereof.

In another embodiment, the invention embraces compounds of formula Ib, where R⁵ is hydrogen and R⁶ is C₁-C₆ alkyl optionally substituted with phenyl, for example benzyl or phenylethyl, and all salts, stereoisomers, mixtures of stereoisomers, prodrugs, metabolites, solvates, and hydrates thereof.

In another embodiment, the invention embraces compounds of formula Ib, where R⁵ is hydrogen and R⁶ is C₁-C₆ alkyl optionally substituted with heterocyclyl or heteroaryl; and all salts, stereoisomers, mixtures of stereoisomers, prodrugs, metabolites, solvates, and hydrates thereof.

In another embodiment, the invention embraces compounds of formula Ib, where R⁵ is hydrogen and R⁶ is C₁-C₆ alkyl optionally substituted with a nitrogen containing heterocyclyl , and all salts, stereoisomers, mixtures of stereoisomers, prodrugs, metabolites, solvates, and hydrates thereof. In another embodiment the invention embraces compounds of formula Ib, where R⁵ is hydrogen and R⁶ is C₁-C₆ alkyl optionally substituted with pyrrolidinyl, piperidinyl, piperazinyl, or morpholinyl, and all salts, stereoisomers, mixtures of stereoisomers, prodrugs, metabolites, solvates, and hydrates thereof.

In another embodiment, the invention embraces compounds of formula Ib, where R⁵ is hydrogen and R⁶ is C₁-C₆ alkyl optionally substituted with a nitrogen containing heteroaryl, for example imidazolyl, pyridinyl, pyrrolyl, and pyrimidinyl and all salts, stereoisomers, mixtures of stereoisomers, prodrugs, metabolites, solvates, and hydrates thereof.

In another embodiment, the invention embraces compounds of formula Ib, where R⁵ is hydrogen and R⁶ is C₁-C₆ alkyl optionally substituted with an oxygen or sulfur containing heterocyclyl or heteroaryl, for example tetrahydropyranyl, tetrahydrofuranyl, tetrahydrothienyl, pyranyl, furanyl or thienyl; and all salts, stereoisomers, mixtures of stereoisomers, prodrugs, metabolites, solvates, and hydrates thereof.

In another embodiment, the invention embraces compounds of formula Ib, where R⁵ and R⁶ together with the nitrogen atom to which they are attached form an optionally substituted 3 to 8-membered nitrogen containing heterocyclyl ring, for example an azetidine, a pyrrolidine, a piperidine, a piperazine, a morpholine or an azepane ring; and all salts, stereoisomers, mixtures of stereoisomers, prodrugs, metabolites, solvates, and hydrates thereof.

In another embodiment, the invention embraces compounds of formula Ib, where R⁵ and R⁶ together with the nitrogen atom to which they are attached form piperidin-1-yl, 4-hydroxy-piperidin-1-yl, 4-methyl-piperazin-1-yl, 4-benzyl-piperazin-1-yl, and azepan-1-yl and all salts, stereoisomers, mixtures of stereoisomers, prodrugs, metabolites, solvates, and hydrates thereof.

In another embodiment, the invention embraces compounds of formula Ib, where R⁵ and R⁶ together with the nitrogen atom to which they are attached form a N,N′-disubstituted piperazine where the nitrogen substitution at the 4-position is a group identical to the substitution at the 1-position forming a compound of formula Ibb, where R¹, R², R³, and R⁴ are as defined above:

and all salts, stereoisomers, mixtures of stereoisomers, prodrugs, metabolites, solvates, and hydrates thereof.

In another embodiment, the invention embraces compounds of formula Ib, where M and M′ are selected from hydrogen, —C(O)—H or —C(O)—C₁-C₆₋alkyl, for example hydrogen or acetyl, and all salts, stereoisomers, mixtures of stereoisomers, prodrugs, metabolites, solvates, and hydrates thereof.

In another embodiment, the invention embraces compounds of formula Ib, where R¹, R², R³, and R⁴ are methyl and M and M′ are hydrogen or C(O)—R¹², and a salt, a stereoisomer, or a mixture of stereoisomers. In another embodiment, the invention embraces compounds of formula Ib, where R¹, R², R³, and R⁴ are methyl and M and M′ are hydrogen or acetyl, and a salt, a stereoisomer, or a mixture of stereoisomers.

In another embodiment, the invention embraces a method of treating or suppressing a mitochondrial disorder, modulating one or more energy biomarkers, normalizing one or more energy biomarkers, or enhancing one or more energy biomarkers, by administering a therapeutically effective amount of one or more compounds of formula I, formula Ia, formula Iaa, formula Ib, or formula Ibb; or of the embodiments of formula I, formula Ia, formula Iaa, formula Ib, or formula Ibb; and all salts, stereoisomers, mixtures of stereoisomers, prodrugs, metabolites, solvates, and hydrates thereof.

In another embodiment, the invention embraces a method of treating or suppressing a mitochondrial disorder, modulating one or more energy biomarkers, normalizing one or more energy biomarkers, or enhancing one or more energy biomarkers, by administering a therapeutically effective amount of one or more compounds of formula Ia, where R¹, R², R³ and R⁴ are independently selected from —C₁-C₄ alkyl; and all salts, stereoisomers, mixtures of stereoisomers, prodrugs, metabolites, solvates, and hydrates thereof.

In another embodiment, the invention embraces a method of treating or suppressing a mitochondrial disorder, modulating one or more energy biomarkers, normalizing one or more energy biomarkers, or enhancing one or more energy biomarkers, by administering a therapeutically effective amount of a stereoisomer compound of formula Ia, where R¹, R², R³ and R⁴ are independently selected from —C₁-C₄ alkyl; and where R⁴ has an (R) configuration; and prodrugs, metabolites, solvates, and hydrates thereof.

In another embodiment, the invention embraces a method of treating or suppressing a mitochondrial disorder, modulating one or more energy biomarkers, normalizing one or more energy biomarkers, or enhancing one or more energy biomarkers, by administering a therapeutically effective amount of a stereoisomer compound of formula Ia, where R¹, R², R³, and R⁴ are independently selected from —C₁-C₄ alkyl; and where R⁴ has an (S) configuration; and prodrugs, metabolites, solvates, and hydrates thereof.

In another embodiment, the invention embraces a method of treating or suppressing a mitochondrial disorder, modulating one or more energy biomarkers, normalizing one or more energy biomarkers, or enhancing one or more energy biomarkers, by administering a therapeutically effective amount or effective amount of one or more compounds of formula Ib, where R¹, R², R³, and R⁴ are independently selected from —C₁-C₄ alkyl; and all salts, stereoisomers, mixtures of stereoisomers, prodrugs, metabolites, solvates, and hydrates thereof.

In another embodiment, the invention embraces a method of treating or suppressing a mitochondrial disorder, modulating one or more energy biomarkers, normalizing one or more energy biomarkers, or enhancing one or more energy biomarkers, by administering a therapeutically effective amount of a stereoisomer compound of formula Ib, where R¹, R², R³, and R⁴ are independently selected from —C₁-C₄-alkyl; and where R⁴ has an (R) configuration; and prodrugs, metabolites, solvates, and hydrates thereof.

In another embodiment, the invention embraces a method of treating or suppressing a mitochondrial disorder, modulating one or more energy biomarkers, normalizing one or more energy biomarkers, or enhancing one or more energy biomarkers, by administering a therapeutically effective amount of a stereoisomer compound of formula Ib, where R¹, R², R³, and R⁴ are independently selected from —C₁-C₄ alkyl; and where R⁴ has an (S) configuration; and prodrugs, metabolites, solvates, and hydrates thereof.

In another embodiment, the invention embraces compounds of formula I, selected from:

-   2-hydroxy-N-isopropyl-2-methyl-4-(2,4,5-trimethyl-3,6-dioxocyclohexa-1,4-dienyl)butanamide; -   2-hydroxy-N-(2-hydroxyethyl)-2-methyl-4-(2,4,5-trimethyl-3,6-dioxocyclohexa-1,4-dienyl)butanamide; -   2-(3-hydroxy-3-methyl-4-oxo-4-(piperidin-1-yl)butyl)-3,5,6-trimethylcyclohexa-2,5-diene-1,4-dione; -   2-(4-(azepan-1-yl)-3-hydroxy-3-methyl-4-oxobutyl)-3,5,6-trimethylcyclohexa-2,5-diene-1,4-dione; -   N-hexyl-2-hydroxy-2-methyl-4-(2,4,5-trimethyl-3,6-dioxocyclohexa-1,4-dienyl)butanamide; -   N-tert-butyl-2-hydroxy-2-methyl-4-(2,4,5-trimethyl-3,6-dioxocyclohexa-1,4-dienyl)butanamide; -   2-hydroxy-N,N,2-trimethyl-4-(2,4,5-trimethyl-3,6-dioxocyclohexa-1,4-dienyl)butanamide; -   N-ethyl-2-hydroxy-2-methyl-4-(2,4,5-trimethyl-3,6-dioxocyclohexa-1,4-dienyl)butanamide; -   N-benzyl-2-hydroxy-2-methyl-4-(2,4,5-trimethyl-3,6-dioxocyclohexa-1,4-dienyl)butanamide; -   2-hydroxy-2-methyl-N-propyl-4-(2,4,5-trimethyl-3,6-dioxocyclohexa-1,4-dienyl)butanamide; -   N-(cyclopropylmethyl)-2-hydroxy-2-methyl-4-(2,4,5-trimethyl-3,6-dioxocyclohexa-1,4-dienyl)butanamide; -   2-hydroxy-2-methyl-N-phenethyl-4-(2,4,5-trimethyl-3,6-dioxocyclohexa-1,4-dienyl)butanamide; -   2-hydroxy-N-(3-hydroxypropyl)-2-methyl-4-(2,4,5-trimethyl-3,6-dioxocyclohexa-1,4-dienyl)butanamide; -   2-hydroxy-N-isopentyl-2-methyl-4-(2,4,5-trimethyl-3,6-dioxocyclohexa-1,4-dienyl)butanamide; -   N-cyclopropyl-2-hydroxy-2-methyl-4-(2,4,5-trimethyl-3,6-dioxocyclohexa-1,4-dienyl)butanamide; -   2-(3-hydroxy-4-(4-hydroxypiperidin-1-yl)-3-methyl-4-oxobutyl)-3,5,6-trimethylcyclohexa-2,5-diene-1,4-dione; -   2-hydroxy-N-isobutyl-2-methyl-4-(2,4,5-trimethyl-3,6-dioxocyclohexa-1,4-dienyl)butanamide; -   N-ethyl-2-hydroxy-N,2-dimethyl-4-(2,4,5-trimethyl-3,6-dioxocyclohexa-1,4-dienyl)butanamide; -   2-hydroxy-2-methyl-4-(2,4,5-trimethyl-3,6-dioxocyclohexa-1,4-dienyl)butanamide; -   2-hydroxy-N-(4-hydroxybutyl)-2-methyl-4-(2,4,5-trimethyl-3,6-dioxocyclohexa-1,4-dienyl)butanamide; -   2-hydroxy-N-(5-hydroxypentyl)-2-methyl-4-(2,4,5-trimethyl-3,6-dioxocyclohexa-1,4-dienyl)butanamide; -   2-hydroxy-N-(2-methoxyethyl)-2-methyl-4-(2,4,5-trimethyl-3,6-dioxocyclohexa-1,4-dienyl)butanamide; -   2-hydroxy-N-(1-hydroxypropan-2-yl)-2-methyl-4-(2,4,5-trimethyl-3,6-dioxocyclohexa-1,4-dienyl)butanamide; -   (R)-2-hydroxy-N-(2-hydroxyethyl)-2-methyl-4-(2,4,5-trimethyl-3,6-dioxocyclohexa-1,4-dienyl)butanamide; -   (S)-2-hydroxy-N-(2-hydroxyethyl)-2-methyl-4-(2,4,5-trimethyl-3,6-dioxocyclohexa-1,4-dienyl)butanamide; -   methyl     2-(2-hydroxy-2-methyl-4-(2,4,5-trimethyl-3,6-dioxocyclohexa-1,4-dienyl)butanamido)acetate; -   N-(3-(1H-imidazol-1-yl)propyl)-2-hydroxy-2-methyl-4-(2,4,5-trimethyl-3,6-dioxocyclohexa-1,4-dienyl)butanamide; -   2-hydroxy-N-(2-(2-hydroxyethoxy)ethyl)-2-methyl-4-(2,4,5-trimethyl-3,6-dioxocyclohexa-1,4-dienyl)butanamide; -   2-hydroxy-2-methyl-N-(pyridin-2-ylmethyl)-4-(2,4,5-trimethyl-3,6-dioxocyclohexa-1,4-dienyl)butanamide; -   2-hydroxy-2-methyl-N-(2-(pyridin-2-yl)ethyl)-4-(2,4,5-trimethyl-3,6-dioxocyclohexa-1,4-dienyl)butanamide; -   2-hydroxy-2-methyl-N-(3-(2-oxopyrrolidin-1-yl)propyl)-4-(2,4,5-trimethyl-3,6-dioxocyclohexa-1,4-dienyl)butanamide; -   2-hydroxy-N-(2-hydroxypropyl)-2-methyl-4-(2,4,5-trimethyl-3,6-dioxocyclohexa-1,4-dienyl)butanamide; -   2-hydroxy-N-(6-hydroxyhexyl)-2-methyl-4-(2,4,5-trimethyl-3,6-dioxocyclohexa-1,4-dienyl)butanamide; -   2-(3-hydroxy-3-methyl-4-(4-methylpiperazin-1-yl)-4-oxobutyl)-3,5,6-trimethylcyclohexa-2,5-diene-1,4-dione; -   2-(4-(4-benzylpiperazin-1-yl)-3-hydroxy-3-methyl-4-oxobutyl)-3,5,6-trimethylcyclohexa-2,5-diene-1,4-dione; -   2-hydroxy-2-methyl-N-((tetrahydrofuran-2-yl)methyl)-4-(2,4,5-trimethyl-3,6-dioxocyclohexa-1,4-dienyl)butanamide; -   2-hydroxy-2-methyl-N-(3-morpholinopropyl)-4-(2,4,5-trimethyl-3,6-dioxocyclohexa-1,4-dienyl)butanamide     ; -   2-hydroxy-N-methoxy-N,2-dimethyl-4-(2,4,5-trimethyl-3,6-dioxocyclohexa-1,4-dienyl)butanamide; -   2-hydroxy-N,N-bis(2-hydroxyethyl)-2-methyl-4-(2,4,5-trimethyl-3,6-dioxocyclohexa-1,4-dienyl)butanamide; -   N-(2-(dimethylamino)ethyl)-2-hydroxy-2-methyl-4-(2,4,5-trimethyl-3,6-dioxocyclohexa-1,4-dienyl)butanamide; -   2-hydroxy-N-(4-hydroxyphenethyl)-2-methyl-4-(2,4,5-trimethyl-3,6-dioxocyclohexa-1,4-dienyl)butanamide; -   N-(3-(dimethylamino)propyl)-2-hydroxy-2-methyl-4-(2,4,5-trimethyl-3,6-dioxocyclohexa-1,4-dienyl)butanamide; -   6,6′-(4,4′-(piperazine-1,4-diyl)bis(3-hydroxy-3-methyl-4-oxobutane-4,1-diyl))bis(2,3,5-trimethylcyclohexa-2,5-diene-1,4-dione); -   N-butyl-2-hydroxy-2-methyl-4-(2,4,5-trimethyl-3,6-dioxocyclohexa-1,4-dienyl)butanamide; -   2-hydroxy-N-(2-hydroxyethyl)-N,2-dimethyl-4-(2,4,5-trimethyl-3,6-dioxocyclohexa-1,4-dienyl)butanamide; -   N,N-diethyl-2-hydroxy-2-methyl-4-(2,4,5-trimethyl-3,6-dioxocyclohexa-1,4-dienyl)butanamide; -   tert-butyl     2-(2-hydroxy-2-methyl-4-(2,4,5-trimethyl-3,6-dioxocyclohexa-1,4-dienyl)butanamido)ethylcarbamate; -   2-hydroxy-2-methyl-N-(pyridin-4-ylmethyl)-4-(2,4,5-trimethyl-3,6-dioxocyclohexa-1,4-dienyl)butanamide; -   2-hydroxy-2-methyl-N-(pyridin-3-ylmethyl)-4-(2,4,5-trimethyl-3,6-dioxocyclohexa-1,4-dienyl)butanamide; -   2-hydroxy-2-methyl-N-(3-(methylsulfonyl)propyl)-4-(2,4,5-trimethyl-3,6-dioxocyclohexa-1,4-dienyl)butanamide; -   2-(2-hydroxy-2-methyl-4-(2,4,5-trimethyl-3,6-dioxocyclohexa-1,4-dienyl)butanamido)acetic     acid; -   2-(4-(4-acetylpiperazin-1-yl)-3-hydroxy-3-methyl-4-oxobutyl)-3,5,6-trimethylcyclohexa-2,5-diene-1,4-dione; -   2-(4-(4-fluoropiperidin-1-yl)-3-hydroxy-3-methyl-4-oxobutyl)-3,5,6-trimethylcyclohexa-2,5-diene-1,4-dione; -   2-(4-(4,4-difluoropiperidin-1-yl)-3-hydroxy-3-methyl-4-oxobutyl)-3,5,6-trimethylcyclohexa-2,5-diene-1,4-dione; -   2-(3-hydroxy-3-methyl-4-oxo-4-(piperazin-1-yl)butyl)-3,5,6-trimethylcyclohexa-2,5-diene-1,4-dione; -   tert-butyl     4-(2-hydroxy-2-methyl-4-(2,4,5-trimethyl-3,6-dioxocyclohexa-1,4-dienyl)butanoyl)piperazine-1-carboxylate; -   2-(4-(4-benzoylpiperazin-1-yl)-3-hydroxy-3-methyl-4-oxobutyl)-3,5,6-trimethylcyclohexa-2,5-diene-1,4-dione; -   (R)-2-hydroxy-2-methyl-4-(2,4,5-trimethyl-3,6-dioxocyclohexa-1,4-dienyl)butanamide; -   (S)-2-hydroxy-2-methyl-4-(2,4,5-trimethyl-3,6-dioxocyclohexa-1,4-dienyl)butanamide; -   2-(3-hydroxy-4-(4-isopropylpiperazin-1-yl)-3-methyl-4-oxobutyl)-3,5,6-trimethylcyclohexa-2,5-diene-1,4-dione; -   2-(4-(4-(cyclopropanecarbonyl)piperazin-1-yl)-3-hydroxy-3-methyl-4-oxobutyl)-3,5,6-trimethylcyclohexa-2,5-diene-1,4-dione; -   (R)-2-(4-(4-acetylpiperazin-1-yl)-3-hydroxy-3-methyl-4-oxobutyl)-3,5,6-trimethylcyclohexa-2,5-diene-1,4-dione; -   (S)-2-(4-(4-acetylpiperazin-1-yl)-3-hydroxy-3-methyl-4-oxobutyl)-3,5,6-trimethylcyclohexa-2,5-diene-1,4-dione; -   (R)-2-(3-hydroxy-4-(4-hydroxypiperidin-1-yl)-3-methyl-4-oxobutyl)-3,5,6-trimethylcyclohexa-2,5-diene-1,4-dione; -   (S)-2-(3-hydroxy-4-(4-hydroxypiperidin-1-yl)-3-methyl-4-oxobutyl)-3,5,6-trimethylcyclohexa-2,5-diene-1,4-dione; -   N-(2-fluorophenethyl)-2-hydroxy-2-methyl-4-(2,4,5-trimethyl-3,6-dioxocyclohexa-1,4-dienyl)butanamide; -   N-(3-fluorophenethyl)-2-hydroxy-2-methyl-4-(2,4,5-trimethyl-3,6-dioxocyclohexa-1,4-dienyl)butanamide; -   N-(4-fluorophenethyl)-2-hydroxy-2-methyl-4-(2,4,5-trimethyl-3,6-dioxocyclohexa-1,4-dienyl)butanamide; -   N-(2-chlorophenethyl)-2-hydroxy-2-methyl-4-(2,4,5-trimethyl-3,6-dioxocyclohexa-1,4-dienyl)butanamide; -   N-(3-chlorophenethyl)-2-hydroxy-2-methyl-4-(2,4,5-trimethyl-3,6-dioxocyclohexa-1,4-dienyl)butanamide; -   N-(4-chlorophenethyl)-2-hydroxy-2-methyl-4-(2,4,5-trimethyl-3,6-dioxocyclohexa-1,4-dienyl)butanamide; -   2-hydroxy-N-(4-methoxyphenyl)-2-methyl-4-(2,4,5-trimethyl-3,6-dioxocyclohexa-1,4-dienyl)butanamide; -   N-(4-fluorophenyl)-2-hydroxy-2-methyl-4-(2,4,5-trimethyl-3,6-dioxocyclohexa-1,4-dienyl)butanamide; -   N-(4-chlorophenyl)-2-hydroxy-2-methyl-4-(2,4,5-trimethyl-3,6-dioxocyclohexa-1,4-dienyl)butanamide; -   N-(2-fluorobenzyl)-2-hydroxy-2-methyl-4-(2,4,5-trimethyl-3,6-dioxocyclohexa-1,4-dienyl)butanamide; -   N-(3-fluorobenzyl)-2-hydroxy-2-methyl-4-(2,4,5-trimethyl-3,6-dioxocyclohexa-1,4-dienyl)butanamide; -   N-(4-fluorobenzyl)-2-hydroxy-2-methyl-4-(2,4,5-trimethyl-3,6-dioxocyclohexa-1,4-dienyl)butanamide; -   N-(2-chlorobenzyl)-2-hydroxy-2-methyl-4-(2,4,5-trimethyl-3,6-dioxocyclohexa-1,4-dienyl)butanamide; -   N-(3-chlorobenzyl)-2-hydroxy-2-methyl-4-(2,4,5-trimethyl-3,6-dioxocyclohexa-1,4-dienyl)butanamide; -   N-(4-chlorobenzyl)-2-hydroxy-2-methyl-4-(2,4,5-trimethyl-3,6-dioxocyclohexa-1,4-dienyl)butanamide;     and all salts, stereoisomers, mixtures of stereoisomers, prodrugs,     metabolites, solvates, and hydrates thereof.

In other embodiments, including any of the foregoing embodiments, the mitochondrial disorder is selected from the group consisting of inherited mitochondrial diseases; Myoclonic Epilepsy with Ragged Red Fibers (MERRF); Mitochondrial Myopathy, Encephalopathy, Lactacidosis, and Stroke (MELAS); Leber's Hereditary Optic Neuropathy (LHON); Leigh Disease; Kearns-Sayre Syndrome (KSS); Friedreich's Ataxia (FA); other myopathies; cardiomyopathy; encephalomyopathy; renal tubular acidosis; neurodegenerative diseases; Parkinson's Disease; Alzheimer's Disease; Amyotrophic Lateral Sclerosis (ALS); motor neuron diseases; other neurological diseases; epilepsy; genetic diseases; Huntington's Disease; mood disorders; schizophrenia; bipolar disorder; age-associated diseases; cerebral vascular accidents, macular degeneration; diabetes; and cancer.

In another embodiment, including any of the foregoing embodiments, the mitochondrial disorder is a mitochondrial respiratory chain disorder. In a particular embodiment, the mitochondrial respiratory chain disorder is a respiratory protein chain disorder. In another particular embodiment, the disorder is CoQ10 deficiency.

In another embodiment, including any of the foregoing embodiments, the mitochondrial disorder is selected from the group consisting of inherited mitochondrial diseases; Myoclonic Epilepsy with Ragged Red Fibers (MERRF); Mitochondrial Myopathy, Encephalopathy, Lactacidosis, and Stroke (MELAS); Leber's Hereditary Optic Neuropathy (LHON); Leigh Disease; Kearns-Sayre Syndrome (KSS); Friedreich's Ataxia (FA).

In another embodiment of the invention, including any of the foregoing embodiments, the mitochondrial disorder is Friedreich's Ataxia (FA). In another embodiment of the invention, the mitochondrial disorder is Leber's Hereditary Optic Neuropathy (LHON). In another embodiment of the invention, including any of the foregoing embodiments, the mitochondrial disorder is mitochondrial myopathy, encephalopathy, lactacidosis, and stroke (MELAS). In another embodiment of the invention, including any of the foregoing embodiments, the mitochondrial disorder is Kearns-Sayre Syndrome (KSS). In another embodiment of the invention, the mitochondrial disorder is Myoclonic Epilepsy with Ragged Red Fibers (MERRF). In another embodiment of the invention, including any of the foregoing embodiments, the disorder is Parkinson's Disease. In another embodiment of the invention, including any of the foregoing embodiments, the disorder is Huntington's Disease. In another embodiment of the invention including any of the foregoing embodiments, the disorder is amyotrophic lateral sclerosis (ALS). In yet another embodiment of the invention including any of the foregoing embodiments, the disorders are cerebral vascular accidents, such as stroke.

In another embodiment of the invention, including any of the foregoing embodiments, the compounds described herein are administered to subjects suffering from a mitochondrial disorder to modulate one or more of various energy biomarkers, including, but not limited to, lactic acid (lactate) levels, either in whole blood, plasma, cerebrospinal fluid, or cerebral ventricular fluid; pyruvic acid (pyruvate) levels, either in whole blood, plasma, cerebrospinal fluid, or cerebral ventricular fluid; lactate/pyruvate ratios, either in whole blood, plasma, cerebrospinal fluid, or cerebral ventricular fluid; phosphocreatine levels, NADH (NADH+H⁺) or NADPH(NADPH+H⁺) levels; NAD or NADP levels; ATP levels; reduced coenzyme Q (CoQ^(red)) levels; oxidized coenzyme Q (CoQ^(ox)) levels; total coenzyme Q (CoQ^(tot)) levels; oxidized cytochrome C levels; reduced cytochrome C levels; oxidized cytochrome C/reduced cytochrome C ratio; acetoacetate levels; beta-hydroxy butyrate levels; acetoacetate/beta-hydroxy butyrate ratio; 8-hydroxy-2′-deoxyguanosine (8-OHdG) levels; levels of reactive oxygen species; oxygen consumption (VO2), carbon dioxide output (VCO2), respiratory quotient (VCO2/VO2), and to modulate exercise intolerance (or conversely, modulate exercise tolerance) and to modulate anaerobic threshold. Energy biomarkers can be measured in whole blood, plasma, cerebrospinal fluid, cerebroventricular fluid, arterial blood, venous blood, or any other body fluid, body gas, or other biological sample useful for such measurement. In one embodiment, the levels are modulated to a value within about 2 standard deviations of the value in a healthy subject. In another embodiment, the levels are modulated to a value within about 1 standard deviation of the value in a healthy subject. In another embodiment, the levels in a subject are changed by at least about 10% above or below the level in the subject prior to modulation. In another embodiment, the levels are changed by at least about 20% above or below the level in the subject prior to modulation. In another embodiment, the levels are changed by at least about 30% above or below the level in the subject prior to modulation. In another embodiment, the levels are changed by at least about 40% above or below the level in the subject prior to modulation. In another embodiment, the levels are changed by at least about 50% above or below the level in the subject prior to modulation. In another embodiment, the levels are changed by at least about 75% above or below the level in the subject prior to modulation. In another embodiment, the levels are changed by at least about 100% above or at least about 90% below the level in the subject prior to modulation.

In another embodiment of the invention, including any of the foregoing embodiments, the compounds described herein are administered to treat subjects suffering from pervasive development disorders selected from Autistic Disorder, Asperger's Disorder, Childhood Disintegrative Disorder (CDD), Rett's Disorder, and Pervasive Developmental Disorder-Not Otherwise Specified (PDD-NOS). In another embodiment, the disorder is Austistic Disorder.

In another embodiment, including any of the foregoing embodiments, the subject or subjects in which a method of treating or suppressing a mitochondrial disorder, modulating one or more energy biomarkers, normalizing one or more energy biomarkers, or enhancing one or more energy biomarkers is performed is/are selected from the group consisting of subjects undergoing strenuous or prolonged physical activity; subjects with chronic energy problems; subjects with chronic respiratory problems; pregnant females; pregnant females in labor; neonates; premature neonates; subjects exposed to extreme environments; subjects exposed to hot environments; subjects exposed to cold environments; subjects exposed to environments with lower-than-average oxygen content; subjects exposed to environments with higher-than-average carbon dioxide content; subjects exposed to environments with higher-than-average levels of air pollution; airline travelers; flight attendants; subjects at elevated altitudes; subjects living in cities with lower-than-average air quality; subjects working in enclosed environments where air quality is degraded; subjects with lung diseases; subjects with lower-than-average lung capacity; tubercular patients; lung cancer patients; emphysema patients; cystic fibrosis patients; subjects recovering from surgery; subjects recovering from illness; elderly subjects; elderly subjects experiencing decreased energy; subjects suffering from chronic fatigue; subjects suffering from chronic fatigue syndrome; subjects undergoing acute trauma; subjects in shock; subjects requiring acute oxygen administration; subjects requiring chronic oxygen administration; or other subjects with acute, chronic, or ongoing energy demands who can benefit from enhancement of energy biomarkers.

In another embodiment, the invention embraces one or more compounds of formula I, Ia, Ib, Iaa, and/or Ibb, in combination with a pharmaceutically acceptable excipient, carrier, or vehicle.

In another embodiment, the invention embraces the use of one or more compounds of formula I, Ia, Ib, Iaa, and/or Ibb, in the therapy of mitochondrial disease. In another embodiment, the invention embraces the use of one or more compounds of formula I, Ia, Ib, Iaa, and/or Ibb in the manufacture of a medicament for use in therapy of mitochondrial disease.

For all of the compounds and methods described above, the quinone form can also be used in its reduced (hydroquinone) form when desired. Likewise, the hydroquinone form can also be used in its oxidized (quinone) form when desired.

MODES FOR CARRYING OUT THE INVENTION

The invention embraces compounds useful in treating or suppressing mitochondrial disorders, and methods of using such compounds for modulation of energy biomarkers. The redox active therapeutics for treatment or suppression of mitochondrial diseases and associated aspects of the invention are described in more detail herein.

By “subject,” “individual,” or “patient” is meant an individual organism, preferably a vertebrate, more preferably a mammal, most preferably a human.

“Treating” a disease with the compounds and methods discussed herein is defined as administering one or more of the compounds discussed herein, with or without additional therapeutic agents, in order to reduce or eliminate either the disease or one or more symptoms of the disease, or to retard the progression of the disease or of one or more symptoms of the disease, or to reduce the severity of the disease or of one or more symptoms of the disease. “Suppression” of a disease with the compounds and methods discussed herein is defined as administering one or more of the compounds discussed herein, with or without additional therapeutic agents, in order to suppress the clinical manifestation of the disease, or to suppress the manifestation of adverse symptoms of the disease. The distinction between treatment and suppression is that treatment occurs after adverse symptoms of the disease are manifest in a subject, while suppression occurs before adverse symptoms of the disease are manifest in a subject. Suppression may be partial, substantially total, or total. Because many of the mitochondrial disorders are inherited, genetic screening can be used to identify patients at risk of the disease. The compounds and methods of the invention can then be administered to asymptomatic patients at risk of developing the clinical symptoms of the disease, in order to suppress the appearance of any adverse symptoms. “Therapeutic use” of the compounds discussed herein is defined as using one or more of the compounds discussed herein to treat or suppress a disease, as defined above. An “effective amount” of a compound is an amount of the compound sufficient to modulate, normalize, or enhance one or more energy biomarkers (where modulation, normalization, and enhancement are defined below). A “therapeutically effective amount” of a compound is an amount of the compound, which, when administered to a subject, is sufficient to reduce or eliminate either a disease or one or more symptoms of a disease, or to retard the progression of a disease or of one or more symptoms of a disease, or to reduce the severity of a disease or of one or more symptoms of a disease, or to suppress the clinical manifestation of a disease, or to suppress the manifestation of adverse symptoms of a disease. A therapeutically effective amount can be given in one or more administrations. An “effective amount” of a compound embraces both a therapeutically effective amount, as well as an amount effective to modulate, normalize, or enhance one or more energy biomarkers in a subject.

“Modulation” of, or to “modulate,” an energy biomarker means to change the level of the energy biomarker towards a desired value, or to change the level of the energy biomarker in a desired direction (e.g., increase or decrease). Modulation can include, but is not limited to, normalization and enhancement as defined below.

“Normalization” of, or to “normalize,” an energy biomarker is defined as changing the level of the energy biomarker from a pathological value towards a normal value, where the normal value of the energy biomarker can be 1) the level of the energy biomarker in a healthy person or subject, or 2) a level of the energy biomarker that alleviates one or more undesirable symptoms in the person or subject. That is, to normalize an energy biomarker which is depressed in a disease state means to increase the level of the energy biomarker towards the normal (healthy) value or towards a value which alleviates an undesirable symptom; to normalize an energy biomarker which is elevated in a disease state means to decrease the level of the energy biomarker towards the normal (healthy) value or towards a value which alleviates an undesirable symptom.

“Enhancement” of, or to “enhance,” energy biomarkers means to intentionally change the level of one or more energy biomarkers away from either the normal value, or the value before enhancement, in order to achieve a beneficial or desired effect. For example, in a situation where significant energy demands are placed on a subject, it may be desirable to increase the level of ATP in that subject to a level above the normal level of ATP in that subject. Enhancement can also be of beneficial effect in a subject suffering from a disease or pathology such as a mitochondrial disease, in that normalizing an energy biomarker may not achieve the optimum outcome for the subject; in such cases, enhancement of one or more energy biomarkers can be beneficial, for example, higher-than-normal levels of ATP, or lower-than-normal levels of lactic acid (lactate) can be beneficial to such a subject.

By modulating, normalizing, or enhancing the energy biomarker Coenzyme Q is meant modulating, normalizing, or enhancing the variant or variants of Coenzyme Q which is predominant in the species of interest. For example, the variant of Coenzyme Q which predominates in humans is Coenzyme Q10. If a species or subject has more than one variant of Coenzyme Q present in significant amounts (i.e., present in amounts which, when modulated, normalized, or enhanced, can have a beneficial effect on the species or subject), modulating, normalizing, or enhancing Coenzyme Q can refer to modulating, normalizing or enhancing any or all variants of Coenzyme Q present in the species or subject.

While the compounds described herein can occur and can be used as the neutral (non-salt) compound, the description is intended to embrace all salts of the compounds described herein, as well as methods of using such salts of the compounds. In one embodiment, the salts of the compounds comprise pharmaceutically acceptable salts. Pharmaceutically acceptable salts are those salts which can be administered as drugs or pharmaceuticals to humans and/or animals and which, upon administration, retain at least some of the biological activity of the free compound (neutral compound or non-salt compound). The desired salt of a basic compound may be prepared by methods known to those of skill in the art by treating the compound with an acid. Examples of inorganic acids include, but are not limited to, hydrochloric acid, hydrobromic acid, sulfuric acid, nitric acid, and phosphoric acid. Examples of organic acids include, but are not limited to, formic acid, acetic acid, propionic acid, glycolic acid, pyruvic acid, oxalic acid, maleic acid, malonic acid, succinic acid, fumaric acid, tartaric acid, citric acid, benzoic acid, cinnamic acid, mandelic acid, sulfonic acids, and salicylic acid. Salts of basic compounds with amino acids, such as aspartate salts and glutamate salts, can also be prepared. The desired salt of an acidic compound can be prepared by methods known to those of skill in the art by treating the compound with a base. Examples of inorganic salts of acid compounds include, but are not limited to, alkali metal and alkaline earth salts, such as sodium salts, potassium salts, magnesium salts, and calcium salts; ammonium salts; and aluminum salts. Examples of organic salts of acid compounds include, but are not limited to, procaine, dibenzylamine, N-ethylpiperidine, N,N-dibenzylethylenediamine, and triethylamine salts. Salts of acidic compounds with amino acids, such as lysine salts, can also be prepared. Additional salts particularly useful for pharmaceutical preparations are described in Berge S. M. et al., “Pharmaceutical salts,” J. Pharm. Sci. 1977 January; 66(1):1-19.

The invention also includes all stereoisomers of the compounds, including diastereomers and enantiomers. The invention also includes mixtures of stereoisomers in any ratio, including, but not limited to, racemic mixtures. Unless stereochemistry is explicitly indicated in a structure, the structure is intended to embrace all possible stereoisomers of the compound depicted. If stereochemistry is explicitly indicated for one portion or portions of a molecule, but not for another portion or portions of a molecule, the structure is intended to embrace all possible stereoisomers for the portion or portions where stereochemistry is not explicitly indicated.

For the purpose of the invention, the compounds of Formula I, and all other compounds disclosed herein, either generically or specifically, include derivatives wherein one or more hydrogen atoms have been replaced by a hydrogen isotope, for example by deuterium.

The compounds can be administered in prodrug form. Prodrugs are derivatives of the compounds, which are themselves relatively inactive but which convert into the active compound when introduced into the subject in which they are used by a chemical or biological process in vivo, such as an enzymatic conversion. Suitable prodrug formulations include, but are not limited to, peptide conjugates of the compounds of the invention and esters of compounds of the inventions. Further discussion of suitable prodrugs is provided in H. Bundgaard, Design of Prodrugs, New York: Elsevier, 1985; in R. Silverman, The Organic Chemistry of Drug Design and Drug Action, Boston: Elsevier, 2004; in R. L. Juliano (ed.), Biological Approaches to the Controlled Delivery of Drugs (Annals of the New York Academy of Sciences, v. 507), New York: New York Academy of Sciences, 1987; and in E. B. Roche (ed.), Design of Biopharmaceutical Properties Through Prodrugs and Analogs (Symposium sponsored by Medicinal Chemistry Section, APhA Academy of Pharmaceutical Sciences, November 1976 national meeting, Orlando, Fla.), Washington: The Academy, 1977.

Metabolites of the compounds are also embraced by the invention.

“C₁-C₆ alkyl” is intended to embrace a saturated linear, branched, cyclic, or a combination thereof, hydrocarbon of 1 to 6 carbon atoms. Examples of “C₁-C₆ alkyl” are methyl, ethyl, n-propyl, isopropyl, cyclopropyl, n-butyl, isobutyl, sec-butyl, t-butyl, cyclobutyl, cyclopropyl-methyl, methyl-cyclopropyl, pentyl where the point of attachment of the pentyl group to the remainder of the molecule can be at any location on the pentyl fragment, cyclopentyl, hexyl where the point of attachment of the hexyl group to the remainder of the molecule can be at any location on the hexyl fragment, and cyclohexyl.

“Halogen” or “halo” designates fluoro, chloro, bromo, and iodo.

“C₁-C₆ haloalkyl” is intended to embrace any C₁-C₆ alkyl substituent having at least one halogen substituent; the halogen can be attached via any valence on the C₁-C₆ alkyl group. Some examples of C₁-C₆ haloalkyl is —CF₃, —CCl₃, —CHF₂, —CHCl₂, —CHBr2, —CH2F, —CH2Cl.

The term “aryl” is intended to embrace an aromatic cyclic hydrocarbon group of from 6 to 20 carbon atoms having a single ring (e.g., phenyl) or multiple condensed (fused) rings (e.g., naphthyl or anthryl).

The term “Friedreich's Ataxia” is intended to embrace other ataxias, and is also sometimes referred to as hereditary ataxia, familiar ataxia, or Friedreich's tabes.

The terms “heterocycle”, “heterocyclic”, “heterocyclo”, and “heterocyclyl” is intended to encompass a monovalent, saturated, or partially unsaturated, carbocyclic radical having one or more rings incorporating one, two, three or four heteroatoms within the ring (chosen from nitrogen, oxygen, and/or sulfur). Examples of heterocycles include morpholine, piperidine, piperazine, thiazolidine, pyrazolidine, pyrazoline, imidazolidine, pyrrolidine, tetrahydropyran, tetrahydrofuran, quinuclidine, and the like.

The terms “heteroaryl”, is intended to encompass a monovalent aromatic, carbocyclic radical having one or more rings incorporating one, two, three or four heteroatoms within the ring (chosen from nitrogen, oxygen, and/or sulfur). Examples of heteroaryl include pyridine, pyrazine, imidazoline, thiazole, isothiazole, pyrazine, triazine, pyrimidine, pyridazine, pyrazole, thiophene, pyrrole, pyran, furan, indole, quinoline, quinazoline, benzimidazole, benzothiophene, benzofuran, benzoxazole, benzothiazole, benzotriazole, imidazo-pyridines, pyrazolo-pyridines, pyrazolo-pyrazine, acridine, carbazole, and the like.

The terms “Parkinson's”, (also called “Parkinsonism” and “Parkinsonian syndrome”) (“PD”) is intended to include not only Parkinson's disease but also drug-induced Parkinsonism and post-encephalitic Parkinsonism. Parkinson's disease is also known as paralysis agitans or shaking palsy. It is characterized by tremor, muscular rigidity and loss of postural reflexes. The disease usually progresses slowly with intervals of 10 to 20 years elapsing before the symptoms cause incapacity. Due to their mimicry of effects of Parkinson's disease, treatment of animals with methamphetamine or MPTP has been used to generate models for Parkinson's disease. These animal models have been used to evaluate the efficacy of various therapies for Parkinson's disease.

Diseases Amenable to Treatment or Suppression with Compounds and Methods of the Invention

A variety of diseases are believed to be caused or aggravated by mitochondrial disorders and impaired energy processing, and can be treated or suppressed using the compounds and methods of the invention. Such diseases include, but are not limited to, inherited mitochondrial diseases, such as Myoclonic Epilepsy with Ragged Red Fibers (MERRF), Mitochondrial Myopathy, Encephalopathy, Lactacidosis, and Stroke (MELAS), Leber's Hereditary Optic Neuropathy (LHON, also referred to as Leber's Disease, Leber's Optic Atrophy (LOA), or Leber's Optic Neuropathy (LON)), Leigh Disease or Leigh Syndrome, Kearns-Sayre Syndrome (KSS), Friedreich's Ataxia (FA), other myopathies (including cardiomyopathy and encephalomyopathy), and renal tubular acidosis; neurodegenerative diseases, such as Parkinson's disease, Alzheimer's disease, amyotrophic lateral sclerosis (ALS, also known as Lou Gehrig's disease), motor neuron diseases; other neurological diseases such as epilepsy; genetic diseases such as Huntington's Disease (which is also a neurological disease); mood disorders such as schizophrenia and bipolar disorder; cerebral vascular accidents such as stroke, and certain age-associated diseases, particularly diseases for which CoQ10 has been proposed for treatment, such as macular degeneration, diabetes, and cancer. Mitochondrial dysfunction is also implicated in excitoxic, neuronal injury, such as that associated with seizures, stroke and ischemia. Mitochondrial dysfunction is also implicated in certain patients suffering from pervasive development disorders selected from Autistic Disorder, Asperger's Disorder, Childhood Disintegrative Disorder (CDD), Rett's Disorder, and Pervasive Developmental Disorder-Not Otherwise Specified (PDD-NOS), and those disorders can also be treated or suppressed using the compounds and methods of the invention.

Clinical Assessment of Mitochondrial Dysfunction and Efficacy of Therapy

Several readily measurable clinical markers are used to assess the metabolic state of patients with mitochondrial disorders. These markers can also be used as indicators of the efficacy of a given therapy, as the level of a marker is moved from the pathological value to the healthy value. These clinical markers include, but are not limited to, one or more of the previously discussed energy biomarkers, such as lactic acid (lactate) levels, either in whole blood, plasma, cerebrospinal fluid, or cerebral ventricular fluid; pyruvic acid (pyruvate) levels, either in whole blood, plasma, cerebrospinal fluid, or cerebral ventricular fluid; lactate/pyruvate ratios, either in whole blood, plasma, cerebrospinal fluid, or cerebral ventricular fluid; phosphocreatine levels, NADH (NADH+H⁺) or NADPH(NADPH+H⁺) levels; NAD or NADP levels; ATP levels; anaerobic threshold; reduced coenzyme Q (CoQ^(red)) levels; oxidized coenzyme Q (CoQ^(ox)) levels; total coenzyme Q (CoQ^(tot)) levels; oxidized cytochrome C levels; reduced cytochrome C levels; oxidized cytochrome C/reduced cytochrome C ratio; acetoacetate levels, β-hydroxy butyrate levels, acetoacetate/β-hydroxy butyrate ratio, 8-hydroxy-2′-deoxyguanosine (8-OHdG) levels; levels of reactive oxygen species; and levels of oxygen consumption (VO2), levels of carbon dioxide output (VCO2), and respiratory quotient (VCO2/VO2). Several of these clinical markers are measured routinely in exercise physiology laboratories, and provide convenient assessments of the metabolic state of a subject. In one embodiment of the invention, the level of one or more energy biomarkers in a patient suffering from a mitochondrial disease, such as Friedreich's ataxia, Leber's hereditary optic neuropathy, MELAS, or KSS, is improved to within two standard deviations of the average level in a healthy subject. In another embodiment of the invention, the level of one or more of these energy biomarkers in a patient suffering from a mitochondrial disease, such as Friedreich's ataxia, Leber's hereditary optic neuropathy, MELAS, or KSS is improved to within one standard deviation of the average level in a healthy subject. Exercise intolerance can also be used as an indicator of the efficacy of a given therapy, where an improvement in exercise tolerance (i.e., a decrease in exercise intolerance) indicates efficacy of a given therapy.

Several metabolic biomarkers have already been used to evaluate efficacy of CoQ10, and these metabolic biomarkers can be monitored as energy biomarkers for use in the methods of the current invention. Pyruvate, a product of the anaerobic metabolism of glucose, is removed by reduction to lactic acid in an anaerobic setting or by oxidative metabolism, which is dependent on a functional mitochondrial respiratory chain. Dysfunction of the respiratory chain may lead to inadequate removal of lactate and pyruvate from the circulation and elevated lactate/pyruvate ratios are observed in mitochondrial cytopathies (see Scriver C R, The metabolic and molecular bases of inherited disease, 7th ed., New York: McGraw-Hill, Health Professions Division, 1995; and Munnich et al., J. Inherit. Metab. Dis. 15(4):448-55 (1992)). Blood lactate/pyruvate ratio (Chariot et al., Arch. Pathol. Lab. Med. 118(7):695-7 (1994)) is, therefore, widely used as a noninvasive test for detection of mitochondrial cytopathies (see again Scriver C R, The metabolic and molecular bases of inherited disease, 7th ed., New York: McGraw-Hill, Health Professions Division, 1995; and Munnich et al., J. Inherit. Metab. Dis. 15(4):448-55 (1992)) and toxic mitochondrial myopathies (Chariot et al., Arthritis Rheum. 37(4):583-6 (1994)). Changes in the redox state of liver mitochondria can be investigated by measuring the arterial ketone body ratio (acetoacetate/3-hydroxybutyrate: AKBR) (Ueda et al., J. Cardiol. 29(2):95-102 (1997)). Urinary excretion of 8-hydroxy-2′-deoxyguanosine (8-OHdG) often has been used as a biomarker to assess the extent of repair of ROS-induced DNA damage in both clinical and occupational settings (Erhola et al., FEBS Lett. 409(2):287-91 (1997); Honda et al., Leuk. Res. 24(6):461-8 (2000); Pilger et al., Free Radic. Res. 35(3):273-80 (2001); Kim et al. Environ Health Perspect 112(6):666-71 (2004)).

Magnetic resonance spectroscopy (MRS) has been useful in the diagnoses of mitochondrial cytopathy by demonstrating elevations in cerebrospinal fluid (CSF) and cortical white matter lactate using proton MRS (1H-MRS) (Kaufmann et al., Neurology 62(8):1297-302 (2004)). Phosphorous MRS (31P-MRS) has been used to demonstrate low levels of cortical phosphocreatine (PCr) (Matthews et al., Ann. Neurol. 29(4):435-8 (1991)), and a delay in PCr recovery kinetics following exercise in skeletal muscle (Matthews et al., Ann. Neurol. 29(4):435-8 (1991); Barbiroli et al., J. Neurol. 242(7):472-7 (1995); Fabrizi et al., J. Neurol. Sci. 137(1):20-7 (1996)). A low skeletal muscle PCr has also been confirmed in patients with mitochondrial cytopathy by direct biochemical measurements.

Exercise testing is particularly helpful as an evaluation and screening tool in mitochondrial myopathies. One of the hallmark characteristics of mitochondrial myopathies is a reduction in maximal whole body oxygen consumption (VO2max) (Taivassalo et al., Brain 126(Pt 2):413-23 (2003)). Given that VO2max is determined by cardiac output (Qc) and peripheral oxygen extraction (arterial-venous total oxygen content) difference, some mitochondrial cytopathies affect cardiac function where delivery can be altered; however, most mitochondrial myopathies show a characteristic deficit in peripheral oxygen extraction (A-V O2 difference) and an enhanced oxygen delivery (hyperkinetic circulation) (Taivassalo et al., Brain 126(Pt 2):413-23 (2003)). This can be demonstrated by a lack of exercise induced deoxygenation of venous blood with direct AV balance measurements (Taivassalo et al., Ann. Neurol. 51(1):38-44 (2002)) and non-invasively by near infrared spectroscopy (Lynch et al., Muscle Nerve 25(5):664-73 (2002); van Beekvelt et al., Ann. Neurol. 46(4):667-70 (1999)).

Several of these energy biomarkers are discussed in more detail as follows. It should be emphasized that, while certain energy biomarkers are discussed and enumerated herein, the invention is not limited to modulation, normalization or enhancement of only these enumerated energy biomarkers.

Lactic acid (lactate) levels: Mitochondrial dysfunction typically results in abnormal levels of lactic acid, as pyruvate levels increase and pyruvate is converted to lactate to maintain capacity for glycolysis. Mitochondrial dysfunction can also result in abnormal levels of NADH+H⁺, NADPH+H⁺, NAD, or NADP, as the reduced nicotinamide adenine dinucleotides are not efficiently processed by the respiratory chain. Lactate levels can be measured by taking samples of appropriate bodily fluids such as whole blood, plasma, or cerebrospinal fluid. Using magnetic resonance, lactate levels can be measured in virtually any volume of the body desired, such as the brain.

Measurement of cerebral lactic acidosis using magnetic resonance in MELAS patients is described in Kaufmann et al., Neurology 62(8):1297 (2004). Values of the levels of lactic acid in the lateral ventricles of the brain are presented for two mutations resulting in MELAS, A3243G and A8344G. Whole blood, plasma, and cerebrospinal fluid lactate levels can be measured by commercially available equipment such as the YSI 2300 STAT Plus Glucose & Lactate Analyzer (YSI Life Sciences, Ohio).

NAD, NADP, NADH and NADPH levels: Measurement of NAD, NADP, NADH(NADH+H⁺) or NADPH(NADPH+H⁺) can be measured by a variety of fluorescent, enzymatic, or electrochemical techniques, e.g., the electrochemical assay described in US 2005/0067303.

Oxygen consumption (vO₂ or VO2), carbon dioxide output (vCO₂ or VCO2), and respiratory quotient (VCO2/VO2): vO₂ is usually measured either while resting (resting vO₂) or at maximal exercise intensity (vO₂ max). Optimally, both values will be measured. However, for severely disabled patients, measurement of vO₂ max may be impractical. Measurement of both forms of vO₂ is readily accomplished using standard equipment from a variety of vendors, e.g. Korr Medical Technologies, Inc. (Salt Lake City, Utah). VCO2 can also be readily measured, and the ratio of VCO2 to VO2 under the same conditions (VCO2/VO2, either resting or at maximal exercise intensity) provides the respiratory quotient (RQ).

Oxidized Cytochrome C, reduced Cytochrome C, and ratio of oxidized Cytochrome C to reduced Cytochrome C: Cytochrome C parameters, such as oxidized cytochrome C levels (Cyt C_(ox)), reduced cytochrome C levels (Cyt C_(red)), and the ratio of oxidized cytochrome C/reduced cytochrome C ratio (Cyt C_(ox))/(Cyt C_(red)), can be measured by in vivo near infrared spectroscopy. See, e.g., Rolfe, P., “In vivo near-infrared spectroscopy,” Annu. Rev. Biomed. Eng. 2:715-54 (2000) and Strangman et al., “Non-invasive neuroimaging using near-infrared light” Biol. Psychiatry 52:679-93 (2002).

Exercise tolerance/Exercise intolerance: Exercise intolerance is defined as “the reduced ability to perform activities that involve dynamic movement of large skeletal muscles because of symptoms of dyspnea or fatigue” (Piña et al., Circulation 107:1210 (2003)). Exercise intolerance is often accompanied by myoglobinuria, due to breakdown of muscle tissue and subsequent excretion of muscle myoglobin in the urine. Various measures of exercise intolerance can be used, such as time spent walking or running on a treadmill before exhaustion, time spent on an exercise bicycle (stationary bicycle) before exhaustion, and the like. Treatment with the compounds or methods of the invention can result in about a 10% or greater improvement in exercise tolerance (for example, about a 10% or greater increase in time to exhaustion, e.g. from 10 minutes to 11 minutes), about a 20% or greater improvement in exercise tolerance, about a 30% or greater improvement in exercise tolerance, about a 40% or greater improvement in exercise tolerance, about a 50% or greater improvement in exercise tolerance, about a 75% or greater improvement in exercise tolerance, or about a 100% or greater improvement in exercise tolerance. While exercise tolerance is not, strictly speaking, an energy biomarker, for the purposes of the invention, modulation, normalization, or enhancement of energy biomarkers includes modulation, normalization, or enhancement of exercise tolerance.

Similarly, tests for normal and abnormal values of pyruvic acid (pyruvate) levels, lactate/pyruvate ratio, ATP levels, anaerobic threshold, reduced coenzyme Q (CoQ^(red)) levels, oxidized coenzyme Q (CoQ') levels, total coenzyme Q (CoQ^(tot)) levels, oxidized cytochrome C levels, reduced cytochrome C levels, oxidized cytochrome C/reduced cytochrome C ratio, acetoacetate levels, β-hydroxy butyrate levels, acetoacetate/β-hydroxy butyrate ratio, 8-hydroxy-2′-deoxyguanosine (8-OHdG) levels, and levels of reactive oxygen species are known in the art and can be used to evaluate efficacy of the compounds and methods of the invention. (For the purposes of the invention, modulation, normalization, or enhancement of energy biomarkers includes modulation, normalization, or enhancement of anaerobic threshold.)

Table 1, following, illustrates the effect that various dysfunctions can have on biochemistry and energy biomarkers. It also indicates the physical effect (such as a disease symptom or other effect of the dysfunction) typically associated with a given dysfunction. It should be noted that any of the energy biomarkers listed in the table, in addition to energy biomarkers enumerated elsewhere, can also be modulated, enhanced, or normalized by the compounds and methods of the invention. RQ=respiratory quotient; BMR=basal metabolic rate; HR(CO)=heart rate (cardiac output); T=body temperature (preferably measured as core temperature); AT=anaerobic threshold; pH=blood pH (venous and/or arterial).

TABLE 1 Site of Biochemical Measurable Energy Physical Dysfunction Event Biomarker Effect Respiratory ↑ NADH Δ lactate, Metabolic Chain Δ lactate:pyruvate dyscrasia & ratio; and fatigue Δ acetoacetate:β- hydroxy butyrate ratio Respiratory ↓ H⁺ gradient Δ ATP Organ Chain dependent dysfunction Respiratory ↓ Electron flux Δ VO₂, RQ, BMR, Metabolic Chain ΔT, AT, pH dyscrasia & fatigue Mitochondria & ↓ ATP, ↓ VO₂ Δ Work, ΔHR (CO) Exercise cytosol intolerance Mitochondria & ↓ ATP Δ PCr Exercise cytosol intolerance Respiratory ↓ Cyt C_(Ox/Red) Δ λ ~700-900 nM Exercise Chain (Near Infrared intolerance Spectroscopy) Intermediary ↓ Catabolism Δ C¹⁴-Labeled Metabolic metabolism substrates dyscrasia & fatigue Respiratory ↓ Electron flux Δ Mixed Venous VO₂ Metabolic Chain dyscrasia & fatigue Mitochondria & ↑ Oxidative Δ Tocopherol & Uncertain cytosol stress Tocotrienols, CoQ10, docosahexanoic acid Mitochondria & ↑ Oxidative Δ Glutathione_(red) Uncertain cytosol stress Mitochondria & Nucleic acid Δ8-hydroxy 2-deoxy Uncertain cytosol oxidation guanosine Mitochondria & Lipid oxidation Δ Isoprostane(s), Uncertain cytosol eicasanoids Cell membranes Lipid oxidation Δ Ethane (breath) Uncertain Cell membranes Lipid oxidation Δ Malondialdehyde Uncertain

Treatment of a subject afflicted by a mitochondrial disease in accordance with the methods of the invention may result in the inducement of a reduction or alleviation of symptoms in the subject, e.g., to halt the further progression of the disorder.

Partial or complete suppression of the mitochondrial disease can result in a lessening of the severity of one or more of the symptoms that the subject would otherwise experience. For example, partial suppression of MELAS could result in reduction in the number of stroke-like or seizure episodes suffered.

Any one or any combination of the energy biomarkers described herein provide conveniently measurable benchmarks by which to gauge the effectiveness of treatment or suppressive therapy. Additionally, other energy biomarkers are known to those skilled in the art and can be monitored to evaluate the efficacy of treatment or suppressive therapy.

Use of Compounds for Modulation of Energy Biomarkers

In addition to monitoring energy biomarkers to assess the status of treatment or suppression of mitochondrial diseases, the compounds of the invention can be used in subjects or patients to modulate one or more energy biomarkers. Modulation of energy biomarkers can be done to normalize energy biomarkers in a subject, or to enhance energy biomarkers in a subject.

Normalization of one or more energy biomarkers is defined as either restoring the level of one or more such energy biomarkers to normal or near-normal levels in a subject whose levels of one or more energy biomarkers show pathological differences from normal levels (i.e., levels in a healthy subject), or to change the levels of one or more energy biomarkers to alleviate pathological symptoms in a subject. Depending on the nature of the energy biomarker, such levels may show measured values either above or below a normal value. For example, a pathological lactate level is typically higher than the lactate level in a normal (i.e., healthy) person, and a decrease in the level may be desirable. A pathological ATP level is typically lower than the ATP level in a normal (i.e., healthy) person, and an increase in the level of ATP may be desirable. Accordingly, normalization of energy biomarkers can involve restoring the level of energy biomarkers to within about at least two standard deviations of normal in a subject, more preferably to within about at least one standard deviation of normal in a subject, to within about at least one-half standard deviation of normal, or to within about at least one-quarter standard deviation of normal.

Enhancement of the level of one or more energy biomarkers is defined as changing the extant levels of one or more energy biomarkers in a subject to a level which provides beneficial or desired effects for the subject. For example, a person undergoing strenuous effort or prolonged vigorous physical activity, such as mountain climbing, could benefit from increased ATP levels or decreased lactate levels. As described above, normalization of energy biomarkers may not achieve the optimum state for a subject with a mitochondrial disease, and such subjects can also benefit from enhancement of energy biomarkers. Examples of subjects who could benefit from enhanced levels of one or more energy biomarkers include, but are not limited to, subjects undergoing strenuous or prolonged physical activity, subjects with chronic energy problems, or subjects with chronic respiratory problems. Such subjects include, but are not limited to, pregnant females, particularly pregnant females in labor; neonates, particularly premature neonates; subjects exposed to extreme environments, such as hot environments (temperatures routinely exceeding about 85-86 degrees Fahrenheit or about 30 degrees Celsius for about 4 hours daily or more), cold environments (temperatures routinely below about 32 degrees Fahrenheit or about 0 degrees Celsius for about 4 hours daily or more), or environments with lower-than-average oxygen content, higher-than-average carbon dioxide content, or higher-than-average levels of air pollution (airline travelers, flight attendants, subjects at elevated altitudes, subjects living in cities with lower-than-average air quality, subjects working in enclosed environments where air quality is degraded); subjects with lung diseases or lower-than-average lung capacity, such as tubercular patients, lung cancer patients, emphysema patients, and cystic fibrosis patients; subjects recovering from surgery or illness; elderly subjects, including elderly subjects experiencing decreased energy; subjects suffering from chronic fatigue, including chronic fatigue syndrome; subjects undergoing acute trauma; subjects in shock; subjects requiring acute oxygen administration; subjects requiring chronic oxygen administration; or other subjects with acute, chronic, or ongoing energy demands who can benefit from enhancement of energy biomarkers.

Accordingly, when an increase in a level of one or more energy biomarkers is beneficial to a subject, enhancement of the one or more energy biomarkers can involve increasing the level of the respective energy biomarker or energy biomarkers to about at least one-quarter standard deviation above normal, about at least one-half standard deviation above normal, about at least one standard deviation above normal, or about at least two standard deviations above normal. Alternatively, the level of the one or more energy biomarkers can be increased by about at least 10% above the subject's level of the respective one or more energy biomarkers before enhancement, by about at least 20% above the subject's level of the respective one or more energy biomarkers before enhancement, by about at least 30% above the subject's level of the respective one or more energy biomarkers before enhancement, by about at least 40% above the subject's level of the respective one or more energy biomarkers before enhancement, by about at least 50% above the subject's level of the respective one or more energy biomarkers before enhancement, by about at least 75% above the subject's level of the respective one or more energy biomarkers before enhancement, or by about at least 100% above the subject's level of the respective one or more energy biomarkers before enhancement.

When a decrease in a level of one or more energy biomarkers is desired to enhance one or more energy biomarkers, the level of the one or more energy biomarkers can be decreased by an amount of about at least one-quarter standard deviation of normal in a subject, decreased by about at least one-half standard deviation of normal in a subject, decreased by about at least one standard deviation of normal in a subject, or decreased by about at least two standard deviations of normal in a subject. Alternatively, the level of the one or more energy biomarkers can be decreased by about at least 10% below the subject's level of the respective one or more energy biomarkers before enhancement, by about at least 20% below the subject's level of the respective one or more energy biomarkers before enhancement, by about at least 30% below the subject's level of the respective one or more energy biomarkers before enhancement, by about at least 40% below the subject's level of the respective one or more energy biomarkers before enhancement, by about at least 50% below the subject's level of the respective one or more energy biomarkers before enhancement, by about at least 75% below the subject's level of the respective one or more energy biomarkers before enhancement, or by about at least 90% below the subject's level of the respective one or more energy biomarkers before enhancement.

Use of Compounds in Research Applications, Experimental Systems, and Assays

The compounds of the invention can also be used in research applications. They can be used in vitro, in vivo, or ex vivo experiments to modulate one or more energy biomarkers in an experimental system. Such experimental systems can be cell samples, tissue samples, cell components or mixtures of cell components, partial organs, whole organs, or organisms. Any one or more of the compounds of formula I, Ia, Iaa, Ib, and Ibb, can be used in experimental systems or research applications. Such research applications can include, but are not limited to, use as assay reagents, elucidation of biochemical pathways, or evaluation of the effects of other agents on the metabolic state of the experimental system in the presence/absence of one or more compounds of the invention.

Additionally, the compounds of the invention can be used in biochemical tests or assays. Such tests can include incubation of one or more compounds of the invention with a tissue or cell sample from a subject to evaluate a subject's potential response (or the response of a specific subset of subjects) to administration of said one or more compounds, or to determine which compound of the invention produces the optimum effect in a specific subject or subset of subjects. One such test or assay would involve 1) obtaining a cell sample or tissue sample from a subject in which modulation of one or more energy biomarkers can be assayed; 2) administering one or more compounds of the invention to the cell sample or tissue sample; and 3) determining the amount of modulation of the one or more energy biomarkers after administration of the one or more compounds, compared to the status of the energy biomarker prior to administration of the one or more compounds. Another such test or assay would involve 1) obtaining a cell sample or tissue sample from a subject in which modulation of one or more energy biomarkers can be assayed; 2) administering at least two compounds of the invention to the cell sample or tissue sample; 3) determining the amount of modulation of the one or more energy biomarkers after administration of the at least two compounds, compared to the status of the energy biomarker prior to administration of the at least compounds, and 4) selecting a compound for use in treatment, suppression, or modulation based on the amount of modulation determined in step 3).

Pharmaceutical Formulations

The compounds described herein can be formulated as pharmaceutical compositions by formulation with additives such as pharmaceutically acceptable excipients, pharmaceutically acceptable carriers, and pharmaceutically acceptable vehicles. Suitable pharmaceutically acceptable excipients, carriers and vehicles include processing agents and drug delivery modifiers and enhancers, such as, for example, calcium phosphate, magnesium stearate, talc, monosaccharides, disaccharides, starch, gelatin, cellulose, methyl cellulose, sodium carboxymethyl cellulose, dextrose, hydroxypropyl-β-cyclodextrin, polyvinylpyrrolidinone, low melting waxes, ion exchange resins, and the like, as well as combinations of any two or more thereof. Other suitable pharmaceutically acceptable excipients are described in “Remington's Pharmaceutical Sciences,” Mack Pub. Co., New Jersey (1991), and “Remington: The Science and Practice of Pharmacy,” Lippincott Williams & Wilkins, Philadelphia, 20th edition (2003) and 21st edition (2005), incorporated herein by reference.

A pharmaceutical composition can comprise a unit dose formulation, where the unit dose is a dose sufficient to have a therapeutic or suppressive effect or an amount effective to modulate, normalize, or enhance an energy biomarker. The unit dose may be sufficient as a single dose to have a therapeutic or suppressive effect or an amount effective to modulate, normalize, or enhance an energy biomarker. Alternatively, the unit dose may be a dose administered periodically in a course of treatment or suppression of a disorder, or to modulate, normalize, or enhance an energy biomarker.

Pharmaceutical compositions containing the compounds of the invention may be in any form suitable for the intended method of administration, including, for example, a solution, a suspension, or an emulsion. Liquid carriers are typically used in preparing solutions, suspensions, and emulsions. Liquid carriers contemplated for use in the practice of the present invention include, for example, water, saline, pharmaceutically acceptable organic solvent(s), pharmaceutically acceptable oils or fats, and the like, as well as mixtures of two or more thereof. The liquid carrier may contain other suitable pharmaceutically acceptable additives such as solubilizers, emulsifiers, nutrients, buffers, preservatives, suspending agents, thickening agents, viscosity regulators, stabilizers, and the like. Suitable organic solvents include, for example, monohydric alcohols, such as ethanol, and polyhydric alcohols, such as glycols. Suitable oils include, for example, soybean oil, coconut oil, olive oil, safflower oil, cottonseed oil, and the like. For parenteral administration, the carrier can also be an oily ester such as ethyl oleate, isopropyl myristate, and the like. Compositions of the present invention may also be in the form of microparticles, microcapsules, liposomal encapsulates, and the like, as well as combinations of any two or more thereof.

Time-release or controlled release delivery systems may be used, such as a diffusion controlled matrix system or an erodible system, as described for example in: Lee, “Diffusion-Controlled Matrix Systems”, pp. 155-198 and Ron and Langer, “Erodible Systems”, pp. 199-224, in “Treatise on Controlled Drug Delivery”, A. Kydonieus Ed., Marcel Dekker, Inc., New York 1992. The matrix may be, for example, a biodegradable material that can degrade spontaneously in situ and in vivo for, example, by hydrolysis or enzymatic cleavage, e.g., by proteases. The delivery system may be, for example, a naturally occurring or synthetic polymer or copolymer, for example in the form of a hydrogel. Exemplary polymers with cleavable linkages include polyesters, polyorthoesters, polyanhydrides, polysaccharides, poly(phosphoesters), polyamides, polyurethanes, poly(imidocarbonates) and poly(phosphazenes).

The compounds of the invention may be administered enterally, orally, parenterally, sublingually, by inhalation (e.g. as mists or sprays), rectally, or topically in dosage unit formulations containing conventional nontoxic pharmaceutically acceptable carriers, adjuvants, and vehicles as desired. For example, suitable modes of administration include oral, subcutaneous, transdermal, transmucosal, iontophoretic, intravenous, intraarterial, intramuscular, intraperitoneal, intranasal (e.g. via nasal mucosa), subdural, rectal, gastrointestinal, and the like, and directly to a specific or affected organ or tissue. For delivery to the central nervous system, spinal and epidural administration, or administration to cerebral ventricles, can be used. Topical administration may also involve the use of transdermal administration such as transdermal patches or iontophoresis devices. The term parenteral as used herein includes subcutaneous injections, intravenous, intramuscular, intrasternal injection, or infusion techniques. The compounds are mixed with pharmaceutically acceptable carriers, adjuvants, and vehicles appropriate for the desired route of administration. Oral administration is a preferred route of administration, and formulations suitable for oral administration are preferred formulations. The compounds described for use herein can be administered in solid form, in liquid form, in aerosol form, or in the form of tablets, pills, powder mixtures, capsules, granules, injectables, creams, solutions, suppositories, enemas, colonic irrigations, emulsions, dispersions, food premixes, and in other suitable forms. The compounds can also be administered in liposome formulations. The compounds can also be administered as prodrugs, where the prodrug undergoes transformation in the treated subject to a form which is therapeutically effective. Additional methods of administration are known in the art.

Injectable preparations, for example, sterile injectable aqueous or oleaginous suspensions, may be formulated according to the known art using suitable dispersing or wetting agents and suspending agents. The sterile injectable preparation may also be a sterile injectable solution or suspension in a nontoxic parenterally acceptable diluent or solvent, for example, as a solution in propylene glycol. Among the acceptable vehicles and solvents that may be employed are water, Ringer's solution, and isotonic sodium chloride solution. In addition, sterile, fixed oils are conventionally employed as a solvent or suspending medium. For this purpose any bland fixed oil may be employed including synthetic mono- or diglycerides. In addition, fatty acids such as oleic acid find use in the preparation of injectables.

Solid dosage forms for oral administration may include capsules, tablets, pills, powders, and granules. In such solid dosage forms, the active compound may be admixed with at least one inert diluent such as sucrose, lactose, or starch. Such dosage forms may also comprise additional substances other than inert diluents, e.g., lubricating agents such as magnesium stearate. In the case of capsules, tablets, and pills, the dosage forms may also comprise buffering agents. Tablets and pills can additionally be prepared with enteric coatings.

Liquid dosage forms for oral administration may include pharmaceutically acceptable emulsions, solutions, suspensions, syrups, and elixirs containing inert diluents commonly used in the art, such as water. Such compositions may also comprise adjuvants, such as wetting agents, emulsifying and suspending agents, cyclodextrins, and sweetening, flavoring, and perfuming agents.

The compounds of the present invention can also be administered in the form of liposomes. As is known in the art, liposomes are generally derived from phospholipids or other lipid substances. Liposomes are formed by mono- or multilamellar hydrated liquid crystals that are dispersed in an aqueous medium. Any non-toxic, physiologically acceptable and metabolizable lipid capable of forming liposomes can be used. The present compositions in liposome form can contain, in addition to a compound of the present invention, stabilizers, preservatives, excipients, and the like. The preferred lipids are the phospholipids and phosphatidyl cholines (lecithins), both natural and synthetic. Methods to form liposomes are known in the art. See, for example, Prescott, Ed., Methods in Cell Biology, Volume XIV, Academic Press, New York, N.W., p. 33 et seq (1976).

The invention also provides articles of manufacture and kits containing materials useful for treating or suppressing mitochondrial diseases. The invention also provides kits comprising any one or more of the compounds of formulas I, Ia, Iaa, Ib, Ibb. In some embodiments, the kit of the invention comprises the container described above.

In other aspects, the kits may be used for any of the methods described herein, including, for example, to treat an individual with a mitochondrial disorder, or to suppress a mitochondrial disorder in an individual.

The amount of active ingredient that may be combined with the carrier materials to produce a single dosage form will vary depending upon the host to which the active ingredient is administered and the particular mode of administration. It will be understood, however, that the specific dose level for any particular patient will depend upon a variety of factors including the activity of the specific compound employed, the age, body weight, body area, body mass index (BMI), general health, sex, diet, time of administration, route of administration, rate of excretion, drug combination, and the type, progression, and severity of the particular disease undergoing therapy. The pharmaceutical unit dosage chosen is usually fabricated and administered to provide a defined final concentration of drug in the blood, tissues, organs, or other targeted region of the body. The therapeutically effective amount or effective amount for a given situation can be readily determined by routine experimentation and is within the skill and judgment of the ordinary clinician.

Examples of dosages which can be used are an effective amount within the dosage range of about 0.1 mg/kg to about 300 mg/kg body weight, or within about 1.0 mg/kg to about 100 mg/kg body weight, or within about 1.0 mg/kg to about 50 mg/kg body weight, or within about 1.0 mg/kg to about 30 mg/kg body weight, or within about 1.0 mg/kg to about 10 mg/kg body weight, or within about 10 mg/kg to about 100 mg/kg body weight, or within about 50 mg/kg to about 150 mg/kg body weight, or within about 100 mg/kg to about 200 mg/kg body weight, or within about 150 mg/kg to about 250 mg/kg body weight, or within about 200 mg/kg to about 300 mg/kg body weight, or within about 250 mg/kg to about 300 mg/kg body weight. Compounds of the present invention may be administered in a single daily dose, or the total daily dosage may be administered in divided dosage of two, three or four times daily.

While the compounds of the invention can be administered as the sole active pharmaceutical agent, they can also be used in combination with one or more other agents used in the treatment or suppression of disorders. Representative agents useful in combination with the compounds of the invention for the treatment or suppression of mitochondrial diseases include, but are not limited to, Coenzyme Q, vitamin E, idebenone, MitoQ, vitamins, and antioxidant compounds.

When additional active agents are used in combination with the compounds of the present invention, the additional active agents may generally be employed in therapeutic amounts as indicated in the Physicians' Desk Reference (PDR) 53rd Edition (1999), or such therapeutically useful amounts as would be known to one of ordinary skill in the art.

The compounds of the invention and the other therapeutically active agents can be administered at the recommended maximum clinical dosage or at lower doses. Dosage levels of the active compounds in the compositions of the invention may be varied so as to obtain a desired therapeutic response depending on the route of administration, severity of the disease and the response of the patient. When administered in combination with other therapeutic agents, the therapeutic agents can be formulated as separate compositions that are given at the same time or different times, or the therapeutic agents can be given as a single composition.

The invention will be further understood by the following nonlimiting examples.

In general, the nomenclature used in this Application was generated with the help of naming package within the ChemOffice® version 11.0 suite of programs by CambridgeSoft Corp (Cambridge, Mass.).

Preparation of Compounds of the Invention

The compounds of this invention can be prepared from readily available starting materials using the following general methods and procedures. It will be appreciated that where typical or preferred process conditions (i.e., reaction temperatures, times, mole ratios of reactants, solvents, pressures, etc.) are given, other process conditions can also be used unless otherwise stated. Optimum reaction conditions may vary with the particular reactants or solvent used, but such conditions can be determined by one skilled in the art by routine optimization procedures.

Furthermore, the compounds of this invention will typically contain one or more chiral centers. Accordingly, if desired, such compounds can be prepared or isolated as pure stereoisomers, i.e., as individual enantiomers or diastereomers, or as stereoisomer-enriched mixtures. All such stereoisomers (and enriched mixtures) are included within the scope of this invention, unless otherwise indicated. Pure stereoisomers (or enriched mixtures) may be prepared using, for example, optically active starting materials or stereoselective reagents well-known in the art. Alternatively, racemic mixtures of such compounds can be separated using, for example, chiral column chromatography, chiral resolving agents and the like.

Protocol A Synthesis of 6-hydroxy-2,5,7,8-tetramethylchroman-2-carboxamides

6-Hydroxy-2,5,7,8-tetramethylchroman-2-carboxylic acid (1 equiv.) was dissolved to 0.2 M THF and the stirred pale yellow solution treated with carbonyldiimidazole (CDI) (1.1 equiv.). The reaction was let stir for one hour and a solution of amine (1.1 equiv 0.2 M in THF) was added over one hour and the reaction stirred overnight. The solution was concentrated, dissolved to 0.04 M in CH₂Cl₂ and washed sequentially with half-volumes of 0.5 M HCl, 1.0 M NaHCO₃, saturated NaCl, the organic layer dried over Na₂SO₄ and concentrated. Flash chromatography yielded the desired 6-hydroxy-2,5,7,8-tetramethylchroman-2-carboxamide derivative.

Protocol B Oxidation of 6-hydroxy-2,5,7,8-tetramethylchroman-2-carboxamides

A solution of 6-hydroxy-2,5,7,8-tetramethylchroman-2-carboxamide (1.0 equiv.) in 3 mL AcCN (0.28 M) and a drop of water was cooled to 0° C. A solution of ceric ammonium nitrate (CAN) (2.2 equiv) in water (0.5 M) cooled to 0° C. was added dropwise over 2-3 minutes. The solution was then immediately treated with 10 mL EtOAc and the layers separated. The organic layer was washed 3×5 mL H₂O and the combined aqueous phases back extracted with 3×5 mL EtOAc. The combined organics were washed with 10 mL saturated NaCl and dried over Na₂SO₄. Flash chromatography yielded the desired 2-hydroxy-2-methyl-4-(2,4,5-trimethyl-3,6-dioxocyclohexa-1,4-dienyl)butanamide derivative.

Example 1 N-tert-Butyl-2-hydroxy-2-methyl-4-(2,4,5-trimethyl-3,6-dioxocyclohexa-1,4-dienyl)butanamide

Following the amide coupling procedure described in protocol A, 500 mg 6-hydroxy-2,5,7,8-tetramethylchroman-2-carboxylic acid (2.00 mmol), 355 mg CDI (2.20 mmol) and 160 mg t-butylamine (2.20 mmol) produced 125.1 mg of N-tert-butyl-6-hydroxy-2,5,7,8-tetramethylchroman-2-carboxamide as a white crystalline solid. ¹H NMR (400 MHz, CDCl₃) δ 6.40 (br s, 1H), 4.51 (s, 1H), 2.60 (m, 2H), 2.26 (m, 1H), 2.19 (s, 3H), 2.16 (S, 3H), 2.10 (s, 3H), 1.88 (m, 1H), 1.47 (s, 3H), 1.26 (m, 9H).

Oxidation as described in protocol B, using 95 mg (0.311 mmol) of N-tert-butyl-6-hydroxy-2,5,7,8-tetramethylchroman-2-carboxamide and 358 mg CAN (0.653 mmol) yielded 92.2 mg of N-tert-butyl-2-hydroxy-2-methyl-4-(2,4,5-trimethyl-3,6-dioxocyclohexa-1,4-dienyl)butanamide as a yellow solid.

¹H NMR (400 MHz, CDCl₃) δ 6.61 (br s, 1H), 3.45 (s, 1H), 2.55 (m, 1H), 2.39 (m, 1H), 2.04-1.91 (m, 10H), 1.56 (m, 1H), 1.37 (m, 12H).

Example 2 2-Hydroxy-N,N,2-trimethyl-4-(2,4,5-trimethyl-3,6-dioxocyclohexa-1,4-dienyl)butanamide

Following the amide coupling procedure described in protocol A, 504 mg 6-hydroxy-2,5,7,8-tetramethylchroman-2-carboxylic acid (2.01 mmol), 361 mg CDI (2.23 mmol) and 1.1 mL of a 2.0 M solution of N,N-dimethylamine in THF (2.2 mmol) produced 412 mg of 6-hydroxy-N,N,2,5,7,8-hexamethylchroman-2-carboxamide as amorphous powder.

¹H NMR (400 MHz, CDCl₃) δ 4.31 (s, 1H), 3.26 (s, 3H), 2.85 (S, 3H), 2.80-2.41 (m, 3H), 2.16 (s, 6H), 2.08 (s, 3H), 1.70-1.60 (m, 4H).

Oxidation as described in protocol B, using 138.6 mg (0.50 mmol) of 6-hydroxy-N,N,2,5,7,8-hexamethylchroman-2-carboxamide and 560 mg CAN (1.02 mmol) yielded 139.9 mg of 2-hydroxy-N,N,2-trimethyl-4-(2,4,5-trimethyl-3,6-dioxocyclohexa-1,4-dienyl)butanamide as a yellow oil.

¹H NMR (400 MHz, CDCl₃) δ 5.07 (s, 1H), 2.23 (br s, 3H), 3.07 (br s, 3H), 2.51 (m, 1H), 2.33 (m, 1H), 2.02 (m, 3H), 1.99-1.94 (m, 7H), 1.69 (m, 1H), 1.47 (s, 3H).

Example 3 N-Benzyl-2-hydroxy-2-methyl-4-(2,4,5-trimethyl-3,6-dioxocyclohexa-1,4-dienyl)butanamide

Following the amide coupling procedure described in protocol A, 500 mg 6-hydroxy-2,5,7,8-tetramethylchroman-2-carboxylic acid (2.0 mmol), 362 mg CDI (2.23 mmol) and 235 mg benzylamine (2.20 mmol) produced 507 mg of N-benzyl-6-hydroxy-2,5,7,8-tetramethylchroman-2-carboxamide as a brown oil.

¹H NMR (400 MHz, CDCl₃) δ 7.22 (m, 3H), 7.00 (m, 2H), 6.76 (br t, 1H), 4.81 (s, 1H), 4.50 (m, 1H), 4.35 (m, 1H), 2.62 (m, 2H), 2.45 (m, 1H), 2.16 (s, 3H), 2.11 (S, 6H), 1.92 (m, 1H), 1.58 (s, 3H).

Oxidation as described in protocol B, using 130 mg (0.383 mmol) of N-benzyl-6-hydroxy-2,5,7,8-tetramethylchroman-2-carboxamide and 441 mg CAN (0.805 mmol) yielded 119.7 mg of N-benzyl-2-hydroxy-2-methyl-4-(2,4,5-trimethyl-3,6-dioxocyclohexa-1,4-dienyl)butanamide as a yellow foam.

¹H NMR (400 MHz, CDCl₃) δ 7.26 (m, 6H), 4.42 (m, 2H), 3.57 (s, 1H), 2.56 (m, 1H), 2.36 (m, 1H), 2.04-1.93 (m, 10H), 1.59 (m, 1H), 1.42 (s, 3H).

Example 4 N-Ethyl-2-hydroxy-2-methyl-4-(2,4,5-trimethyl-3,6-dioxocyclohexa-1,4-dienyl)butanamide

Following the amide coupling procedure described in protocol A, 500 mg 6-hydroxy-2,5,7,8-tetramethylchroman-2-carboxylic acid (2.00 mmol), 356 mg CDI (2.20 mmol) and 1.1 mL of a 2.0 solution of ethylamine in methanol (2.2 mmol) produced 334 mg of as N-ethyl-6-hydroxy-2,5,7,8-tetramethylchroman-2-carboxamide as a white solid.

¹H NMR (400 MHz, CDCl₃) δ 6.44 (br s, 1H), 4.40 (s, 1H), 3.24 (m, 2H), 2.57 (m, 2H), 2.31 (m, 1H), 2.18 (s, 6H), 2.10 (s, 3H), 1.89 (m, 1H), 1.49 (s, 3H), 1.07 (t, 3H).

Oxidation as described in protocol B, using 100 mg (0.360 mmol) of N-ethyl-6-hydroxy-2,5,7,8-tetramethylchroman-2-carboxamide and 415 mg CAN (0.757 mmol) yielded 96.2 mg of N-ethyl-2-hydroxy-2-methyl-4-(2,4,5-trimethyl-3,6-dioxocyclohexa-1,4-dienyl)butanamide as a yellow oil.

¹H NMR (400 MHz, CDCl₃) δ 6.87 (br s, 1H), 3.64 (s, 1H), 3.29 (m, 2H), 2.56 (m, 1H), 2.38 (m, 1H), 2.10-1.97 (m, 10H), 1.59 (m, 1H), 1.39 (s, 3H), 1.15 (t, 3H).

Example 5 2-Hydroxy-2-methyl-N-propyl-4-(2,4,5-trimethyl-3,6-dioxocyclohexa-1,4-dienyl)butanamide

Following the amide coupling procedure described in protocol A, 502.3 mg 6-hydroxy-2,5,7,8-tetramethylchroman-2-carboxylic acid (2.01 mmol), 358 mg CDI (2.21 mmol) and 130 mg propylamine (2.20 mmol) produced 371 mg of 6-hydroxy-2,5,7,8-tetramethyl-N-propylchroman-2-carboxamide as an off white syrup.

¹H NMR (400 MHz, CDCl₃) δ 6.50 (br s, 1H), 4.85 (br s, 1H), 3.18 (q, 2H), 2.62 (m, 2H), 2.37 (m, 1H), 2.18 (s, 6H), 2.09 (s, 3H), 1.91 (m, 1H), 1.50 (s, 3H), 1.42 (m, 2H), 0.80 (t, 3H).

Oxidation as described in protocol B, using 90.6 mg (0.311 mmol) of 6-hydroxy-2,5,7,8-tetramethyl-N-propylchroman-2-carboxamide and 374.9 mg CAN (0.684 mmol) yielded 2-hydroxy-2-methyl-N-propyl-4-(2,4,5-trimethyl-3,6-dioxocyclohexa-1,4-dienyl)butanamide as a yellow powder.

¹H NMR (400 MHz, CDCl₃) δ 6.89 (br t, 1H), 3.61 (s, 1H), 2.21 (q, 2H), 2.56 (m, 1H), 2.36 (m, 1H), 2.02 (m, 10H), 1.56 (m, 3H), 1.40 (m, 3H), 0.92 (t, 3H).

Example 6 N-(Cyclopropylmethyl)-2-hydroxy-2-methyl-4-(2,4,5-trimethyl-3,6-dioxocyclohexa-1,4-dienyl)butanamide

Following the amide coupling procedure described in protocol A, 502 mg 6-hydroxy-2,5,7,8-tetramethylchroman-2-carboxylic acid (2.01 mmol), 356 mg CDI (2.20 mmol) and 158 mg cyclopropanemethylamine (2.22 mmol produced 445 mg of N-(cyclopropylmethyl)-6-hydroxy-2,5,7,8-tetramethylchroman-2-carboxamide as a clear colorless oil.

¹H NMR (400 MHz, CDCl₃) δ 6.53 (br s, 1H), 4.39 (s, 1H), 3.05 (m, 2H), 2.57 (m, 2H), 2.31 (m, 2H), 2.17 (s, 6H), 2.08 (s, 3H), 1.90 (m, 1H), 1.50 (m, 3H), 0.86 (m, 1H), 0.40 (m, 2H), 0.070 (m, 2H).

Oxidation as described in protocol B, using 76.7 mg (0.253 mmol) of N-(cyclopropylmethyl)-6-hydroxy-2,5,7,8-tetramethylchroman-2-carboxamide and 435 mg CAN (0.794 mmol) yielded 71.4 mg of N-(cyclopropylmethyl)-2-hydroxy-2-methyl-4-(2,4,5-trimethyl-3,6-dioxocyclohexa-1,4-dienyl)butanamide as a yellow powder.

¹H NMR (400 MHz, CDCl₃) δ 6.93 (br t, 1H), 3.46 (s, 1H), 3.13 (t, 2H), 2.58 (m, 1H), 2.42 (m, 1H), 2.05-1.84 (m, 10H), 1.60 (m, 1H), 1.42 (s, 3H), 0.97 (m, 1H), 0.51 (m, 2H), 0.22 (m, 2H).

Example 7 2-Hydroxy-N-isopentyl-2-methyl-4-(2,4,5-trimethyl-3,6-dioxocyclohexa-1,4-dienyl)butanamide

Following the amide coupling procedure described in protocol A, 492 mg 6-hydroxy-2,5,7,8-tetramethylchroman-2-carboxylic acid (1.97 mmol), 370 mg CDI (2.28 mmol) and 192 mg 3-methylbutamine (2.20 mmol) produced 375 mg of 6-hydroxy-N-isopentyl-2,5,7,8-tetramethylchroman-2-carboxamide as white crystals.

Oxidation as described in protocol B, using 101 mg (0.316 mmol) of 6-hydroxy-N-isopentyl-2,5,7,8-tetramethylchroman-2-carboxamide and 380 mg CAN (0.694 mmol) yielded 101.2 mg of 2-hydroxy-N-isopentyl-2-methyl-4-(2,4,5-trimethyl-3,6-dioxocyclohexa-1,4-dienyl)butanamide as a yellow oil.

¹H NMR (400 MHz, CDCl₃) δ 6.85 (br t, 1H), 3.65 (s, 1H), 3.65 (q, 2H), 2.55 (m, 1H), 2.35 (m, 1H), 2.02-1.95 (m, 10H), 1.59 (m, 2H), 1.43-1.37 (m, 5H), 0.89 (d, 6H).

Example 8 2-Hydroxy-2-methyl-N-phenethyl-4-(2,4,5-trimethyl-3,6-dioxocyclohexa-1,4-dienyl)butanamide

Following the amide coupling procedure described in protocol A, 500 mg 6-hydroxy-2,5,7,8-tetramethylchroman-2-carboxylic acid (2.00 mmol), 356 mg CDI (2.20 mmol) and 266 mg phenethylamine (2.2 mmol) produced 440 mg of 6-hydroxy-2,5,7,8-tetramethyl-N-phenethylchroman-2-carboxamide as aclear pale brown oil.

¹H NMR (400 MHz, CDCl₃) δ 7.21 (m, 3H), 7.05 (m, 2H), 6.46 (bt t, 1H), 4.29 (s, 1H), 3.52 (m, 2H), 2.78-2.57 (m, 3H), 2.48 (m, 1H), 2.33 (dt, 1H), 2.16 (s, 3H), 2.09 (s, 3H), 1.98 (s, 3H), 1.82 (m, 1H), 1.47 (s, 3H).

Oxidation as described in protocol B, using 102 mg (0.287 mmol) of 6-hydroxy-2,5,7,8-tetramethyl-N-phenethylchroman-2-carboxamide and 355 mg CAN (0.647 mmol) yielded 95.8 mg of 2-hydroxy-2-methyl-N-phenethyl-4-(2,4,5-trimethyl-3,6-dioxocyclohexa-1,4-dienyl)butanamide as a yellow oil.

¹H NMR (400 MHz, CDCl₃) δ 7.29 (m, 2H), 7.20 (m, 3H), 6.88 (br t, 1H), 3.54 (m, 2H), 3.32 (s, 1H), 2.84 (t, 2H), 2.48 (m, 1H), 2.29 (m, 1H), 2.02-1.94 (m, 10H), 1.54 (m, 1H), 1.36 (s, 3H).

Example 9 2-Hydroxy-N-(3-hydroxypropyl)-2-methyl-4-(2,4,5-trimethyl-3,6-dioxocyclohexa-1,4-dienyl)butanamide

Following the amide coupling procedure described in protocol A, 500 mg 6-hydroxy-2,5,7,8-tetramethylchroman-2-carboxylic acid (2.00 mmol), 357 mg CDI (2.20 mmol) and 165 mg 3-aminopropanol (2.2 mmol) produced 297 mg of 6-hydroxy-N-(3-hydroxypropyl)-2,5,7,8-tetramethylchroman-2-carboxamide as an amorphous white solid.

¹H NMR (400 MHz, CDCl₃) δ 6.78 (br t, 1H), 4.88 (br s, 1H), 3.50-3.31 (m, 5H), 2.66-2.49 (m, 2H), 2.33 (m, 1H), 2.17 (s, 6H), 2.09 (s, 3H), 1.88 (m, 1H), 1.66-1.51 (m, 5H).

Oxidation as described in protocol B, using 56.7 mg (0.184 mmol) of 6-hydroxy-N-(3-hydroxypropyl)-2,5,7,8-tetramethylchroman-2-carboxamide and 222 mg CAN (0.406 mmol) yielded 49.7 mg of 2-hydroxy-N-(3-hydroxypropyl)-2-methyl-4-(2,4,5-trimethyl-3,6-dioxocyclohexa-1,4-dienyl)butanamide as a yellow solid.

¹H NMR (400 MHz, CDCl₃) δ 7.19 (br t, 1H), 3.65 (q, 2H), 3.58 (br s, 1H), 3.43 (m, 2H), 2.56 (m, 1H), 2.41 (m, 1H), 2.05-1.99 (m, 10H), 1.73 (quintet, 2H), 1.61 (m, 1H), 1.42 (s, 3H).

Example 10 N-Cyclopropyl-2-hydroxy-2-methyl-4-(2,4,5-trimethyl-3,6-dioxocyclohexa-1,4-dienyl)butanamide

Following the amide coupling procedure described in protocol A, 500 mg 6-hydroxy-2,5,7,8-tetramethylchroman-2-carboxylic acid (2.00 mmol), 357 mg CDI (2.00 mmol) and 126 mg cyclopropylamine (2.2 mmol) produced 227 mg of N-cyclopropyl-6-hydroxy-2,5,7,8-tetramethylchroman-2-carboxamide as a pale brown oil.

¹H NMR (400 MHz, CDCl₃) δ 6.50 (br s, 1H), 4.32 (br s, 1H), 2.68-2.58 (m, 3H), 2.32 (m, 1H), 2.17 (s, 3H), 2.14 (s, 3H), 2.09 (s, 3H), 1.87 (m, 1H), 1.48 (s, 3H), 0.75 (m, 2H), 0.38 (m, 2H).

Oxidation as described in protocol B, using 100 mg (0.346 mmol) of N-cyclopropyl-6-hydroxy-2,5,7,8-tetramethylchroman-2-carboxamide and 417 mg CAN (0.762 mmol) yielded 40 mg of N-cyclopropyl-2-hydroxy-2-methyl-4-(2,4,5-trimethyl-3,6-dioxocyclohexa-1,4-dienyl)butanamide as a yellow oil.

¹H NMR (400 MHz, CDCl₃) δ 6.86 (br s, 1H), 3.45 (s, 1H), 2.74 (m, 1H), 2.54 (m, 1H), 2.38 (m, 1H), 2.02-1.98 (m, 9H), 1.77 (d, 1H), 1.58 (m, 1H), 1.39 (s, 3H), 0.79 (q, 2H), 0.53 (m, 2H).

Example 11 2-Hydroxy-N-isobutyl-2-methyl-4-(2,4,5-trimethyl-3,6-dioxocyclohexa-1,4-dienyl)butanamide

Following the amide coupling procedure described in protocol A, 510 mg 6-hydroxy-2,5,7,8-tetramethylchroman-2-carboxylic acid (2.04 mmol), 357 mg CDI (2.20 mmol) and 161 mg isobutylamine (2.2 mmol) produced 467 mg of 6-hydroxy-N-isobutyl-2,5,7,8-tetramethylchroman-2-carboxamide as an off-white solid.

¹H NMR (400 MHz, CDCl₃) δ 6.49 (br s, 1H), 4.29 (s, 1H), 3.09 (m, 1H), 3.00 (m, 1H), 2.59 (m, 2H), 2.36 (dt, 1H), 2.10 (s, 6H), 2.09 (s, 3H), 1.88 (m, 1H), 1.65 (m, 1H), 1.52 (s, 3H), 0.76 (dd, 6H).

Oxidation as described in protocol B, using 84 mg (0.278 mmol) of 6-hydroxy-N-isobutyl-2,5,7,8-tetramethylchroman-2-carboxamide and 335 mg CAN (0.612 mmol) yielded 78 mg of 2-hydroxy-N-isobutyl-2-methyl-4-(2,4,5-trimethyl-3,6-dioxocyclohexa-1,4-dienyl)butanamide as a yellow-orange oil.

¹H NMR (400 MHz, CDCl₃) δ 6.94 (t, 1H), 3.55 (s, 1H), 3.09 (m, 2H), 2.58 (m, 1H), 2.89 (m, 1H), 2.07-1.94 (m, 10H), 1.79 (m, 1H), 1.58 (m, 1H), 1.41 (s, 3H), 0.88 (d, 6H).

Example 12 2-(3-Hydroxy-4-(4-hydroxypiperidin-1-yl)-3-methyl-4-oxobutyl)-3,5,6-trimethylcyclohexa-2,5-diene-1,4-dione

Following the amide coupling procedure described in protocol A, 500 mg 6-hydroxy-2,5,7,8-tetramethylchroman-2-carboxylic acid (2.0 mmol), 370 mg CDI (2.28 mmol) and 222 mg 4-hydroxypiperidine (2.20 mmol) produced 222 mg of a (6-hydroxy-2,5,7,8-tetramethylchroman-2-yl)(4-hydroxypiperidin-1-yl)methanone as a white foam.

¹H NMR (400 MHz, CDCl₃) δ 4.56-4.31 (br d, 1H), 4.27 (br s, 1H), 4.08 (br s, 1H), 3.85 (m, 1H), 3.56-3.46 (br m, 1H), 3.08 (br s, 1H), 3.77 (m, 1H), 2.57 (m, 2H), 2.15 (s, 6H), 2.08 (m, 3H), 1.82 (br s, 2H), 1.69 (m, 1H), 1.58 (br s, 6H).

Oxidation as described in protocol B, using 100 mg (0.302 mmol) of (6-hydroxy-2,5,7,8-tetramethylchroman-2-yl)(4-hydroxypiperidin-1-yl)methanone and 364 mg CAN (0.664 mmol) yielded 95 mg of a yellow syrup.

¹H NMR (400 MHz, CDCl₃) δ 4.00 (m, 4H), 3.45 (m, 3H), 2.53-2.42 (m, 1H), 2.05-1.92 (m, 10H), 1.71 (m, 1H), 1.56 (m, 3H), 1.49 (s, 3H).

Example 13 N-ethyl-2-hydroxy-N,2-dimethyl-4-(2,4,5-trimethyl-3,6-dioxocyclohexa-1,4-dienyl)butanamide

Following the amide coupling procedure described in protocol A, 499 mg 6-hydroxy-2,5,7,8-tetramethylchroman-2-carboxylic acid (2.00 mmol), 360 mg CDI (2.22 mmol) and 130 mg N-methyl ethylamine (2.2 mmol) produced N-ethyl-6-hydroxy-N,2,5,7,8-pentamethylchroman-2-carboxamide as a clear oil.

¹H NMR (400 MHz, CDCl₃) δ 4.30 (br s, 1H), 3.82 (B, m, 2H), 3.44 (A, m, 1H), 3.20 (A, s, 3H), 3.08 (A, m, 1H), 2.82 (B, s, 3H), 2.75 (m, 1H), 2.66-2.52 (m, 2H), 2.16 (s, 6H), 2.08 (s, 3H), 1.70-1.58 (m, 4H), 1.03 (A+B, dt, 3H). two rotomers in 60:40 mixture, A and B

Oxidation as described in protocol B, using 78 mg (0.268 mmol) of N-ethyl-6-hydroxy-N,2,5,7,8-pentamethylchroman-2-carboxamide and 323 mg CAN (0.590 mmol) yielded 76 mg of N-ethyl-2-hydroxy-N,2-dimethyl-4-(2,4,5-trimethyl-3,6-dioxocyclohexa-1,4-dienyl)butanamide as a yellow oil.

¹H NMR (400 MHz, CDCl₃) δ 5.12 (br s, 1H), 3.61 (br s, 1H), 3.40 (br s, 1H), 3.21 (s, 3H), 2.98 (br s, 1H), 2.51 (td, 1H), 2.35 (br s, 1H), 2.02 (s, 3H), 1.97 (s, 6H), 1.67 (td, 1H), 1.46 (s, 3H), 1.80 (br m, 3H).

Example 14 2-(3-Hydroxy-3-methyl-4-(4-methylpiperazin-1-yl)-4-oxobutyl)-3,5,6-trimethylcyclohexa-2,5-diene-1,4-dione

Following the amide coupling procedure described in protocol A, 502 mg 6-hydroxy-2,5,7,8-tetramethylchroman-2-carboxylic acid (2.01 mmol), 354 mg CDI (2.18 mmol) and 220 mg N-methylpiprazine (2.2 mmol) produced 557 mg of (6-hydroxy-2,5,7,8-tetramethylchroman-2-yl)(4-methylpiperazin-1-yl)methanone as a clear oil.

¹H NMR (400 MHz, CDCl₃) δ 4.02 (br s, 2H), 3.56 (br d, 2H), 2.78 (m, 1H), 2.55 (m, 2H), 2.35 (br s, 4H), 2.24 (s, 3H), 2.16 (s, 3H), 2.13 (s, 3H), 2.08 (s, 3H), 1.72 (m, 1H), 1.58 (2, 3H).

Oxidation as described in protocol B, using 122 mg (0.368 mmol) of (6-hydroxy-2,5,7,8-tetramethylchroman-2-yl)(4-methylpiperazin-1-yl)methanone and 444 mg CAN (0.811 mmol) yielded 2-(3-hydroxy-3-methyl-4-(4-methylpiperazin-1-yl)-4-oxobutyl)-3,5,6-trimethylcyclohexa-2,5-diene-1,4-dione as an orange oil, 67.9 mg.

¹H NMR (400 MHz, CDCl₃) δ 4.91 (br s, 1H), 3.77 (br m, 4H), 2.58-2.30 (m, 8H), 2.04-1.76 (m, 10H), 1.71 (m, 1H), 1.48 (s, 3H).

Example 15 2-(4-(4-Benzylpiperazin-1-yl)-3-hydroxy-3-methyl-4-oxobutyl)-3,5,6-trimethylcyclohexa-2,5-diene-1,4-dione

Following the amide coupling procedure described in protocol A, 506 mg 6-hydroxy-2,5,7,8-tetramethylchroman-2-carboxylic acid (2.02 mmol), 365 mg CDI (2.25 mmol) and 386 mg 1-benzylpiperazine (2.2 mmol) yielded 568 mg of (4-benzylpiperazin-1-yl)(6-hydroxy-2,5,7,8-tetramethylchroman-2-yl)methanone as a white powder.

¹H NMR (400 MHz, CDCl₃) δ 7.30 (m, 5H), 5.18 (br s, 1H), 4.06 (br m, 2H), 3.66 (br s, 1H), 3.47 (dd, 2H), 2.78 (m, 1H), 2.58 (m, 2H), 2.39 (m, 5H), 2.18 (s, 3H), 2.14 (s, 3H), 2.08 (s, 3H), 1.74 (m, 1H), 1.60 (s, 3H).

Oxidation as described in protocol B, using 98 mg (0.242 mmol) of (4-benzylpiperazin-1-yl)(6-hydroxy-2,5,7,8-tetramethylchroman-2-yl)methanone and 291 mg CAN (0.531 mmol) yielded 76 mg of 2-(4-(4-benzylpiperazin-1-yl)-3-hydroxy-3-methyl-4-oxobutyl)-3,5,6-trimethylcyclohexa-2,5-diene-1,4-dion as a yellow oil.

¹H NMR (400 MHz, CDCl₃) δ 7.21 (m, 5H), 4.94 (s, 1H), 3.70 (br s, 2H), 3.63 (br s, 2H), 3.98 (dd, 2H), 2.49-2.31 (m, 6H), 1.96 (s, 3H), 1.91 (s, 6H), 1.84 (m, 1H), 1.61 (m, 1H), 1.30 (s, 3H). APCI-MS M⁺+H 425 m/z.

Example 16 2-Hydroxy-2-methyl-4-(2,4,5-trimethyl-3,6-dioxocyclohexa-1,4-dienyl)butanamide

Following the amide coupling procedure described in protocol A, 498 mg 6-hydroxy-2,5,7,8-tetramethylchroman-2-carboxylic acid (1.99 mmol), 367 mg CDI (2.26 mmol) and 1.4 mL of 7.0M NH₃ in MeOH (9.8 mmol) produced 187 mg of 6-hydroxy-2,5,7,8-tetramethylchroman-2-carboxamide as a white solid.

Oxidation as described in protocol B, using 186 mg (0.747 mmol) of 6-hydroxy-2,5,7,8-tetramethylchroman-2-carboxamide and 907 mg CAN (1.65 mmol) yielded 157 mg of 2-hydroxy-2-methyl-4-(2,4,5-trimethyl-3,6-dioxocyclohexa-1,4-dienyl)butanamide as a yellow solid.

¹H NMR (400 MHz, d₄-MeOH) δ 2.71 (ddd, 1H), 2.39 (ddd, 1H), 2.01 (s, 3H), 1.99 (s, 6H), 1.85 (ddd, 1H), 1.58 (m, 1H), 1.38 (s, 3H).

Example 17 2-Hydroxy-N-(4-hydroxybutyl)-2-methyl-4-(2,4,5-trimethyl-3,6-dioxocyclohexa-1,4-dienyl)butanamide

Following the amide coupling procedure described in protocol A, 507 mg 6-hydroxy-2,5,7,8-tetramethylchroman-2-carboxylic acid (2.03 mmol), 356 mg CDI (2.20 mmol) and 196 mg 4-aminobutanol (2.20 mmol) produced 488 mg of 6-hydroxy-N-(4-hydroxybutyl)-2,5,7,8-tetramethylchroman-2-carboxamide as a white powder.

¹H NMR (400 MHz, d₄-MeOH) δ 7.22 (br t, 1H), 3.41 (t, 2H), 3.25 (m, 1H), 3.12 (m, 1H), 2.61 (dt, 1H), 2.50 (m, 1H), 2.32 (dt, 1H), 2.16 (s, 3H), 2.14 (s, 3H), 2.05 (s, 3H), 1.75 (m, 1H), 1.47 (s, 3H), 1.41 (m, 2H), 1.28 (m, 2H).

Oxidation as described in protocol B, using 100 mg (0.311 mmol) of 6-hydroxy-N-(4-hydroxybutyl)-2,5,7,8-tetramethylchroman-2-carboxamide and 375 mg CAN (0.685 mmol) yielded 2-hydroxy-N-(4-hydroxybutyl)-2-methyl-4-(2,4,5-trimethyl-3,6-dioxocyclohexa-1,4-dienyl)butanamide as a yellow solid.

¹H NMR (400 MHz, CDCl₃) δ 7.12 (t, 1H), 3.97 (s, 1H), 3.67 (t, 2H), 3.29 (q, 2H), 2.81 (br s, 1H), 3.56 (td, 1H), 2.34 (td, 1H), 2.02-1.92 (m, 10H), 1.61 (m, 5H), 1.39 (s, 3H).

Example 18 2-Hydroxy-N-(5-hydroxypentyl)-2-methyl-4-(2,4,5-trimethyl-3,6-dioxocyclohexa-1,4-dienyl)butanamide

Following the amide coupling procedure described in protocol A, 497 mg 6-hydroxy-2,5,7,8-tetramethylchroman-2-carboxylic acid (1.98 mmol), 370 mg CDI (2.28 mmol) and 239 mg 5-aminopentanol (2.2 mmol) produced 468 mg of 6-hydroxy-N-(5-hydroxypentyl)-2,5,7,8-tetramethylchroman-2-carboxamide as a pale brown solid.

¹H NMR (400 MHz, d₄-MeOH) δ 7.16 (br t, 1H), 3.42 (t, 2H), 3.07 (m, 1H), 2.60 (dt, 1H), 2.50 (m, 1H), 2.36 (m, 1H), 2.18 (s, 3H), 2.16 (s, 3H), 2.06 (2, 3H), 1.78 (m, 1H), 1.49 (s, 3H), 1.37 (m, 4H), 1.09 (m, 2H).

Oxidation as described in protocol B, using 96 mg (0.286 mmol) of 6-hydroxy-N-(5-hydroxypentyl)-2,5,7,8-tetramethylchroman-2-carboxamide and 345 mg CAN (0.629 mmol) yielded 92.8 mg of 2-hydroxy-N-(5-hydroxypentyl)-2-methyl-4-(2,4,5-trimethyl-3,6-dioxocyclohexa-1,4-dienyl)butanamide as a yellow oil.

¹H NMR (400 MHz, CDCl₃) δ 6.96 (t, 1H), 3.83 (br s, 1H), 3.65 (t, 2H), 3.26 (q, 2H), 2.65 (td, 1H), 2.35 (m, 1H), 2.24 (br s, 1H), 2.02-1.93 (m, 10H), 1.57 (m, 5H), 1.43 (m, 5H).

Example 19 2-Hydroxy-N-(1-hydroxypropan-2-yl)-2-methyl-4-(2,4,5-trimethyl-3,6-dioxocyclohexa-1,4-dienyl)butanamide

Following the amide coupling procedure described in protocol A, 500 mg 6-hydroxy-2,5,7,8-tetramethylchroman-2-carboxylic acid (2.00 mmol), 365 mg CDI (2.25 mmol) and 165 mg 2-amino-1-propanol (2.2 mmol) produced 488 mg of 6-hydroxy-N-(1-hydroxypropan-2-yl)-2,5,7,8-tetramethylchroman-2-carboxamide as a pale brown foam.

¹H NMR (400 MHz, CDCl₃) δ 7.31 (t, 0.4H), 7.21 (t, 0.6H), 3.97 (br s, 1.5H), 3.83 (br s, 0.4H), 3.56 (br s, 0.6H, 3.53-3.44 (m, 1H), 3.67 (br s, 0.4H), 3.16 (m, 1H), 2.58 (m, 1H), 2.36 (m, 1H), 2.03-1.90 (m, 10H), 1.61 (m, 1H), 1.424 (s, 1.4H), 1.416 (s, 1.6H), 1.21 (d, 3H).

Oxidation as described in protocol B, using 102.2 mg (0.329 mmol) of 6-hydroxy-N-(1-hydroxypropan-2-yl)-2,5,7,8-tetramethylchroman-2-carboxamide and 397 mg CAN (2.45 mmol) yielded 98.5 mg of 2-hydroxy-N-(1-hydroxypropan-2-yl)-2-methyl-4-(2,4,5-trimethyl-3,6-dioxocyclohexa-1,4-dienyl)butanamide as a yellow foam.

Example 20 2-Hydroxy-N-(2-hydroxyethyl)-2-methyl-4-(2,4,5-trimethyl-3,6-dioxocyclohexa-1,4-dienyl)butanamide

6-Hydroxy-2,5,7,8-tetramethylchroman-2-carboxylic acid (5.00 g 19.98 mmol) in 150 mL THF was treated with 3.65 g CDI (22.5 mmol) and the exothermic reaction let stir for 1 h at room temperature. Ethanolamine (1.35 g, 22.10 mmol) in 50 mL THF was added over 1 h and the solution stirred overnight. The reaction was concentrated, dissolved into 375 mL CH₂Cl₂ and washed with 250 mL 0.1 M HCl, 250 mL 0.5 M NaHCO₃, 2×100 mL saturated NaCl and dried over Na₂SO₄. The acidic aqueous phase was extracted 3×100 mL CH₂Cl₂ and washed with 50 mL saturated NaCl and dried over Na₂SO₄. The combined organics were concentrated and purified by flash chromatography yielding 2.88 g of 6-hydroxy-N-(2-hydroxyethyl)-2,5,7,8-tetramethylchroman-2-carboxamide as an off white impure solid.

¹H NMR (400 MHz, CDCl₃) δ 6.88 (br s, 1H), 4.35 (t, 2H), 3.62 (m, 2H), 3.39 (m, 2H), 2.60 (m, 2H), 2.50 (t, 2H), 2.34 (m, 1H), 2.27 (m, 1H), 2.18 (s, 6H), 2.09 (s, 3H), 1.90 (m, 1H), 1.53 (s, 3H).

6-Hydroxy-N-(2-hydroxyethyl)-2,5,7,8-tetramethylchroman-2-carboxamide (2.38 g, 8.11 mmol) was dissolved into 150 mL AcCN, cooled to 0° C. and treated with 9.75 g CAN (17.84 mmol) in 30 mL H₂O over 20 minutes. EtOAc (150 mL) and H₂O (20 mL) were then added, layers separated and the organic phase washed 21×20 mL H₂O. The aqueous phase was back extracted 4×50 mL EtOAc and the combined organics washed with saturated NaCl, dried over Na₂SO₄ and concentrated to a yellow powder. Flash chromatography yielded 1.68 g of 2-hydroxy-N-(2-hydroxyethyl)-2-methyl-4-(2,4,5-trimethyl-3,6-dioxocyclohexa-1,4-dienyl)butanamide as a yellow solid.

¹H NMR (400 MHz, d₆-Ace) δ 7.55 (br s, 1H), 4.62 (s, 1H), 3.99 (t, 1H), 3.62 (q, 2H), 3.34 (m, 2H), 2.69 (td, 1H), 2.36 (td, 1H), 1.98 (s, 9H), 1.89 (m, 1H), 1.60 (m, 1H), 1.37 (s, 3H).

Example 21 2-Hydroxy-N-(2-methoxyethyl)-2-methyl-4-(2,4,5-trimethyl-3,6-dioxocyclohexa-1,4-dienyl)butanamide

Following the amide coupling procedure described in protocol A, 499 mg 6-hydroxy-2,5,7,8-tetramethylchroman-2-carboxylic acid (2.00 mmol), 370 mg CDI (2.28 mmol) and 165.2 mg 2-methoxyethylamine (2.20 mmol) produced 6-hydroxy-N-(2-methoxyethyl)-2,5,7,8-tetramethylchroman-2-carboxamide as a white crystalline solid.

Oxidation as described in protocol B, 101 mg (0.329 mmol) of 2-methoxyethylamine (2.20 mmol) yielded 6-hydroxy-N-(2-methoxyethyl)-2,5,7,8-tetramethylchroman-2-carboxamide and 396 mg CAN (0.724 mmol) yielding 2-hydroxy-N-(2-methoxyethyl)-2-methyl-4-(2,4,5-trimethyl-3,6-dioxocyclohexa-1,4-dienyl)butanamide as a yellow crystalline solid.

¹H NMR (400 MHz, CDCl₃) δ 7.14 (br s, 1H), 3.53 (s, 1H), 3.46 (m, 4H), 3.35 (s, 3H), 2.58 (td, 1H), 2.37 (td, 1H), 2.05-1.94 (m, 10H), 1.60 (m, 1H) 1.41 (s, 3H).

Example 22 Methyl 2-(2-hydroxy-2-methyl-4-(2,4,5-trimethyl-3,6-dioxocyclohexa-1,4-dienyl)butanamido)acetate

Following the amide coupling procedure described in protocol A, 499 mg 6-hydroxy-2,5,7,8-tetramethylchroman-2-carboxylic acid (2.00 mmol), and 361 mg CDI (2.23 mmol) were dissolved in THF. Glycine methyl ester hydrochloride (263.7 mg, 2.1 mmol) dissolved into 10 mL THF, 5 mL CH₂Cl₂, 100 μL Et₃N and 2.5 mL MeOH was added over 1 h. Workup as described in protocol A, produced 471.3 mg of methyl 2-(6-hydroxy-2,5,7,8-tetramethylchroman-2-carboxamido)acetate

¹H NMR (400 MHz, CDCl₃) δ 7.02 (br s, 1H), 4.10 (dd, 1H), 3.92 (dd, 1H), 3.72 (s, 3H), 2.61 (m, 2H), 2.35 (m, 1H), 2.22 (s, 3H), 2.18 (s, 3H), 2.09 (s, 3H), 1.91 (m, 1H), 1.53 (s, 3H).

Oxidation as described in protocol B, using 110 mg (0.344 mmol) of methyl 2-(6-hydroxy-2,5,7,8-tetramethylchroman-2-carboxamido)acetate and 415 mg CAN (0.757 mmol) yielded 94.0 mg of methyl 2-(2-hydroxy-2-methyl-4-(2,4,5-trimethyl-3,6-dioxocyclohexa-1,4-dienyl)butanamido)acetate as a yellow powder.

¹H NMR (400 MHz, CDCl₃) δ 7.41 (t, 1H), 4.05 (qd, 2H), 3.74 (s, 3H), 3.62 (br s, 1H), 2.62 (td, 1H), 2.43 (m, 1H), 2.04 (m, 1H), 1.99 (s, 6H), 1.97 (s, 3H), 1.61 (m, 1H), 1.43 (s, 3H).

Example 23 N-(3-(1H-imidazol-1-yl)propyl)-2-hydroxy-2-methyl-4-(2,4,5-trimethyl-3,6-dioxocyclohexa-1,4-dienyl)butanamide

A solution of 6-hydroxy-2,5,7,8-tetramethylchroman-2-carboxylic acid (500 mg, 2.00 mmol) in 10 mL THF was treated with 358 mg CDI and stirred for 1.25 h at room temperature. To this clear yellow solution was added a solution of 278 mg 1-(3-aminopropyl)imidazole in 10 mL THF over 1 h. The solution was stirred overnight at room temperature, concentrated to a pale brown oil, dissolved into 70 mL CH₂Cl₂, washed 1×50 mL saturated NaCl, and dried over Na₂SO₄. The organic layers were concentrated and flashed chromatographed to yield 524 mg of N-(3-(1H-imidazol-1-yl)propyl)-6-hydroxy-2,5,7,8-tetramethylchroman-2-carboxamide as a white crystalline solid.

¹H NMR (400 MHz, CDCl₃) δ 7.22 (s, 1H), 7.02 (s, 1H), 6.58 (s, 1H), 6.41 (t, 1H), 3.71 (quint, 1H), 3.58 (quint, 1H), 3.37 (sextet, 1H), 3.02 (sextet, 1H), 2.34 (dt, 1H), 2.54 (m, 1H), 2.44 (m, 1H), 2.20 (s, 6H), 2.08 (s, 3H), 1.93 (m, 1H), 1.83 (m, 2H), 1.54 (s, 3H).

To a solution of N-(3-(1H-imidazol-1-yl)propyl)-6-hydroxy-2,5,7,8-tetramethylchroman-2-carboxamide (100.7 mg, 0.282 mmol) in 6 mL AcCN and 6 mL CH₂Cl₂, cooled to 0° C., was added a cooled solution of CAN (340 mg, 0.620 mmol) in 2 mL H₂O, dropwise over 5 minutes. The reaction was immediately treated with 5 mL EtOAc and washed 3×3 mL H₂O. The aqueous layer was basified with 6 mL saturated NaHCO₃ solution and extracted 6×3 mL EtOAc. The combined organics were dried over Na₂SO₄ and concentrated to a yellow oil. Flash chromatography yielded 98.1 mg of N-(3-(1H-imidazol-1-yl)propyl)-2-hydroxy-2-methyl-4-(2,4,5-trimethyl-3,6-dioxocyclohexa-1,4-dienyl)butanamide as a yellow solid.

¹H NMR (400 MHz, CDCl₃) δ 7.56 (s, 1H), 7.05 (s, 1H), 6.97 (s, 1H), 4.02 (t, 2H), 3.60 (br s, 1H), 3.29 (m, 2H), 2.60 (td, 1H), 2.37 (td, 1H), 2.07-1.92 (m, 12H), 1.63 (m, 1H), 1.41 (s, 3H)

Example 24 (R)-2-Hydroxy-N-(2-hydroxyethyl)-2-methyl-4-(2,4,5-trimethyl-3,6-dioxocyclohexa-1,4-dienyl)butanamide

Following the amide coupling procedure described in protocol A, 1.846 g 6-hydroxy-2,5,7,8-tetramethylchroman-2-carboxylic acid (7.37 mmol), 1.315 g CDI (8.11 mmol) and 991 mg ethanolamine (16.22 mmol) produced 1.765 g of (R)-6-hydroxy-N-(2-hydroxyethyl)-2,5,7,8-tetramethylchroman-2-carboxamide as a waxy white solid.

¹H NMR (400 MHz, CDCl₃) δ 6.88 (br s, 1H), 3.63 (td, 2H), 3.39 (m, 2H), 2.70-2.54 (m, 2H), 2.35 (dt, 1H), 2.18 (s, 6H), 2.10 (s, 3H), 1.90 (m, 1H), 1.53 (s, 3H).

Oxidation as described in protocol B, using 1.49 g (5.11 mmol) of precursor (R)-6-hydroxy-N-(2-hydroxyethyl)-2,5,7,8-tetramethylchroman-2-carboxamide and 6.16 g CAN (11.2 mmol) yielded 1.46 g of (R)-2-hydroxy-N-(2-hydroxyethyl)-2-methyl-4-(2,4,5-trimethyl-3,6-dioxocyclohexa-1,4-dienyl)butanamide as a waxy yellow solid.

¹H NMR (400 MHz, CDCl₃) δ 7.14 (br s, 1H), 3.78 (t, 2H), 3.48 (m, 2H), 2.59 (m, 1H), 2.39 (m, 1H), 2.04-1.94 (m, 10H), 1.64 (m, 1H), 1.43 (s, 3H).

Example 25 2-Hydroxy-N-(2-(2-hydroxyethoxy)ethyl)-2-methyl-4-(2,4,5-trimethyl-3,6-dioxocyclohexa-1,4-dienyl)butanamide

Following the amide coupling procedure described in protocol A, 501 mg 6-hydroxy-2,5,7,8-tetramethylchroman-2-carboxylic acid (2.0 mmol), 360 mg CDI (2.23 mmol) and 231 mg 2-(2-aminoethoxy)ethanol (2.19 mmol) produced 557 mg of 6-hydroxy-N-(2-(2-hydroxyethoxy)ethyl)-2,5,7,8-tetramethylchroman-2-carboxamide as an amorphous white solid.

¹H NMR (400 MHz, CDCl₃) δ 6.83 (br s, 1H), 3.63 (t, 2H), 3.53-3.36 (m, 6H), 2.60 (m, 2H), 2.35 (dt, 1H), 2.18 (s, 6H), 2.09 (s, 3H), 1.88 (m, 1H), 1.52 (s, 3H).

Oxidation as described in protocol B, using 98.1 mg (0.305 mmol) of 6-hydroxy-N-(2-(2-hydroxyethoxy)ethyl)-2,5,7,8-tetramethylchroman-2-carboxamide and 368 mg CAN (0.671 mmol) yielded 2-hydroxy-N-(2-(2-hydroxyethoxy)ethyl)-2-methyl-4-(2,4,5-trimethyl-3,6-dioxocyclohexa-1,4-dienyl)butanamide as a yellow oil.

¹H NMR (400 MHz, CDCl₃) δ 7.26 (t, 1H), 3.82 (br s, 1H), 3.74 (m, 2H), 3.60 (m, 4H), 3.50 (m, 2H), 2.90 (br s, 1H), 2.57 (td, 1H), 2.38 (m, 1H), 2.03-1.93 (m, 10H), 1.61 (m, 1H), 1.41 (s, 3H).

Example 26 2-Hydroxy-2-methyl-N-(2-(pyridin-2-yl)ethyl)-4-(2,4,5-trimethyl-3,6-dioxocyclohexa-1,4-dienyl)butanamide

Following the amide coupling procedure described in protocol A, 499 mg 6-hydroxy-2,5,7,8-tetramethylchroman-2-carboxylic acid (1.99 mmol), 370 mg CDI (2.28 mmol) and 324 mg 2-picolylamine (3.0 mmol), produced 579 mg of 6-hydroxy-2,5,7,8-tetramethyl-N-(pyridin-2-ylmethyl)chroman-2-carboxamide as a white solid.

¹H NMR (400 MHz, CDCl₃) δ 8.48 (d, 1H), 7.68 (br s, 1H), 7.58 (td, 1H), 7.15 (m, 1H), 7.02 (d, 1H), 4.53 (m, 2H), 4.32 (s, 1H), 2.63 (m, 2H), 2.39 (dt, 1H), 2.25 (s, 3H), 2.17 (s, 3H), 2.09 (s, 3H), 1.93 (m, 1H), 1.56 (s, 3H).

A solution of 6-hydroxy-2,5,7,8-tetramethyl-N-(pyridin-2-ylmethyl)chroman-2-carboxamide (104 mg, 0.307 mmol) in 4 mL AcCN was chilled to 0° C. and CAN (370 mg in 2 mL H₂O) added followed by 8 mL EtOAc, 4 mL 1.0 M NaHCO₃ and 250 mg K₂CO₃. The emulsion was extracted 5×4 mL EtOAc and the combined organics washed 2×4 mL saturated NaCl, dried over Na₂SO₄ and concentrated to yellow oil. Flash chromatography yielded 2-hydroxy-2-methyl-N-(pyridin-2-ylmethyl)-4-(2,4,5-trimethyl-3,6-dioxocyclohexa-1,4-dienyl)butanamide.

¹H NMR (400 MHz, CDCl₃) δ 8.51 (d, 1H), 8.02 (t, 1H), 7.65 (td, 1H), 7.29 (d, 1H), 7.18 (dd, 1H), 4.55 (m, 2H), 4.39 (br s, 1H), 2.63 (m, 1H), 2.34 (m, 1H), 1.99 (m, 1H), 1.96 (s, 3H), 1.93 (s, 6H), 1.66 (m, 1H), 1.46 (s, 3H).

Example 27 2-Hydroxy-2-methyl-N-(2-(pyridin-2-yl)ethyl)-4-(2,4,5-trimethyl-3,6-dioxocyclohexa-1,4-dienyl)butanamide

A solution of 6-hydroxy-2,5,7,8-tetramethylchroman-2-carboxylic acid (500 mg, 2.0 mmol) in 10 mL THF was treated with 356 mg CDI (2.2 mmol). After 1 h, 366 mg 2-(2-methylaminoethyl)pyridine (3.0 mmol) in 10 mL THF was added over 1 h and stirred overnight. The solution was concentrated, dissolved into 70 mL CH₂Cl₂, extracted once with 1.0 M NaHCO₃. The aqueous phase was then back extracted 2×25 mL CH₂Cl₂ and the combined organics washed with 2×25 mL saturated NaCl and dried over Na₂SO₄. The solution was concentrated and purified by flash chromatography to give 6-hydroxy-2,5,7,8-tetramethyl-N-(2-(pyridin-2-yl)ethyl)chroman-2-carboxamide.

¹H NMR (400 MHz, CDCl₃) δ 8.43 (d, 1H), 7.52 (t, 1H), 7.12 (m, 2H), 6.98 (d, 1H), 4.27 (s, 1H), 3.69 (q, 2H), 2.92 (m, 2H), 2.34 (dt, 1H), 2.52 (m, 1H), 2.32 (m, 1H), 2.15 (s, 3H), 2.08 (s, 3H), 2.06 (s, 3H), 1.84 (m, 1H), 1.46 (s, 3H).

6-Hydroxy-2,5,7,8-tetramethyl-N-(2-(pyridin-2-yl)ethyl)chroman-2-carboxamide (97.7 mg, 0.276 mmol) was dissolved in 3 mL AcCN and 2 mL CH₂Cl₂ and cooled to 0° C. prior to treatment with 332.5 mg CAN (0.606 mmol) in 2 mL H₂O. The reaction was quenched by the addition of 5 mL EtOAc and 4 mL 1.0 M NaHCO₃ followed by extraction of the aqueous layer 3×5 mL EtOAc. The combined organics were back extracted 3×3 mL saturated NaCl, dried over Na₂SO₄ and concentrated. Flash chromatography yielded 85.8 mg of 2-hydroxy-2-methyl-N-(2-(pyridin-2-yl)ethyl)-4-(2,4,5-trimethyl-3,6-dioxocyclohexa-1,4-dienyl)butanamide as a yellow oil.

¹H NMR (400 MHz, CDCl₃) δ 8.53 (d, 1H), 7.65 (t, 1H), 7.48 (br t, 1H), 7.21 (m, 2H), 3.71 (q, 2H), 3.04 (t, 2H), 2.52 (m, 1H), 2.34 (m, 1H), 2.00-1.89 (m, 10H), 1.58 (m, 1H), 1.37 (s, 3H).

Example 28 (S)-2-hydroxy-N-(2-hydroxyethyl)-2-methyl-4-(2,4,5-trimethyl-3,6-dioxocyclohexa-1,4-dienyl)butanamide

Following the amide coupling procedure described in protocol A, 5.06 g 6-hydroxy-2,5,7,8-tetramethylchroman-2-carboxylic acid (20.2 mmol), 3.68 g CDI (22.7 mmol) and 2.44 g ethanolamine (39.52 mmol) produced 4.576 g of (S)-6-hydroxy-N-(2-hydroxyethyl)-2,5,7,8-tetramethylchroman-2-carboxamide as a white powder.

¹H NMR (400 MHz, CDCl₃) δ 6.88 (s, 1H), 3.64 (t, 2H), 3.39 (m, 2H), 2.62 (m, 2H), 2.35 (dt, 1H), 2.18 (s, 6H), 2.10 (s, 3H), 1.90 (m, 1H), 1.53 (s, 3H).

Oxidation as described in protocol B, using 3.50 g (11.93 mmol) of (S)-6-hydroxy-N-(2-hydroxyethyl)-2,5,7,8-tetramethylchroman-2-carboxamide and 13.73 g CAN (25.06 mmol) yielded 3.341 g of (S)-2-hydroxy-N-(2-hydroxyethyl)-2-methyl-4-(2,4,5-trimethyl-3,6-dioxocyclohexa-1,4-dienyl)butanamide as a yellow solid.

¹H NMR (400 MHz, CDCl₃) δ 7.24 (t, 1H), 3.75 (t, 2H), 3.47 (m, 2H), 3.29 (s, 2H), 2.58 (td, 1H), 2.35 (td, 1H), 2.00-1.94 (m, 10H), 1.61 (td, 1H), 1.42 (s, 3H).

Example 29 2-Hydroxy-2-methyl-N-(3-(2-oxopyrrolidin-1-yl)propyl)-4-(2,4,5-trimethyl-3,6-dioxocyclohexa-1,4-dienyl)butanamide

Following the amide coupling procedure described in protocol A, 499 mg 6-hydroxy-2,5,7,8-tetramethylchroman-2-carboxylic acid (2.00 mmol), 357 mg CDI (2.2 mmol) and 569 mg 1-(3-aminopropyl)pyrrolidin-2-one (4.0 mmol) yielded 598 mg of 6-hydroxy-2,5,7,8-tetramethyl-N-(3-(2-oxopyrrolidin-1-yl)propyl)chroman-2-carboxamide as a white powder.

¹H NMR (400 MHz, CDCl₃) δ 7.02 (t, 1H), 3.31 (m, 2H), 3.24 (m, 1H), 3.11 (m, 2H), 2.59 (m, 2H), 2.37 (m, 3H), 2.24 (s, 3H), 2.17 (s, 3H), 2.08 (s, 3H), 2.01 (m, 2H), 1.87 (m, 1H), 1.61 (m, 4H). 1.51 (s, 3H).

Oxidation as described in protocol B, using 113.2 mg (0.302 mmol) of 6-hydroxy-2,5,7,8-tetramethyl-N-(3-(2-oxopyrrolidin-1-yl)propyl)chroman-2-carboxamide and 364.6 mg CAN (0.665 mmol) yielded 118 mg of 2-hydroxy-2-methyl-N-(3-(2-oxopyrrolidin-1-yl)propyl)-4-(2,4,5-trimethyl-3,6-dioxocyclohexa-1,4-dienyl)butanamide as a yellow oil.

¹H NMR (400 MHz, CDCl₃) δ 7.52 (br t, 1H), 3.41 (quintet, 4H), 3.26 (m, 2H), 2.58 (td, 1H), 2.42 (m, 3H), 2.09-1.88 (m, 12H), 1.75 (m, 2H), 1.66 (m, 1H), 1.44 (s, 3H).

Example 30 2-Hydroxy-N-(2-hydroxypropyl)-2-methyl-4-(2,4,5-trimethyl-3,6-dioxocyclohexa-1,4-dienyl)butanamide

Following the amide coupling procedure described in protocol A, 4.98 g 6-hydroxy-2,5,7,8-tetramethylchroman-2-carboxylic acid (19.9 mmol), 3.99 g CDI (24.6 mmol) and 3.01 g 3-amino-2-propanol (39.9 mmol), yielded 5.15 g of 6-hydroxy-N-(2-hydroxypropyl)-2,5,7,8-tetramethylchroman-2-carboxamide as a white powder.

¹H NMR (400 MHz, CDCl₃) δ 6.83 (br s, 1H), 3.8 (m, 1H), 3.39 (m, 1H), 3.11 (m, 1H), 2.62 (m, 2H), 2.38 (dt, 1H), 2.19 (s, 6H), 2.09 (s, 3H), 1.88 (m, 1H), 1.53 (s, 3H), 1.07 (dd, 3H).

Oxidation as described in protocol B, using 505 mg (1.64 mmol) of 6-hydroxy-N-(2-hydroxypropyl)-2,5,7,8-tetramethylchroman-2-carboxamide and 1.99 mg CAN (3.62 mmol) yielded 496 mg of 2-hydroxy-N-(2-hydroxypropyl)-2-methyl-4-(2,4,5-trimethyl-3,6-dioxocyclohexa-1,4-dienyl)butanamide as a yellow oil.

¹H NMR (400 MHz, CDCl₃) δ 7.21 (t, 0.5H), 7.07 (t, 0.5H), 3.98 (m, 1H), 3.52 (m, 1H), 3.15 (m, 1H), 2.61 (m, 1H), 2.42 (m, 1H), 2.04-1.91 (m, 10H), 1.63 (m, 1H), 1.42 (s, 1H), 1.24 (m, 3H).

Example 31 2-Hydroxy-N-(6-hydroxyhexyl)-2-methyl-4-(2,4,5-trimethyl-3,6-dioxocyclohexa-1,4-dienyl)butanamide

Following the amide coupling procedure described in protocol A, 500 mg 6-hydroxy-2,5,7,8-tetramethylchroman-2-carboxylic acid (2.0 mmol), 356 mg CDI (2.2 mmol) and 468 mg 6-amino-1-hexanol (4.0 mmol) yielded 161 mg of 6-hydroxy-N-(6-hydroxyhexyl)-2,5,7,8-tetramethylchroman-2-carboxamide as a white solid.

¹H NMR (400 MHz, CDCl₃) δ 6.35 (t, 1H), 3.56 (t, 2H), 3.53 (sextet, 1H), 3.05 (sextet, 1H), 2.58 (m, 2H), 2.42 (dt, 1H), 2.19 (s, 6H), 2.09 (s, 3H), 1.83 (m, 1H), 1.53 (s, 3H), 1.53-1.29 (m, 5H), 1.20 (m, 2H), 0.99 (m, 2H).

Oxidation as described in protocol B, using 64.2 mg (0.183 mmol) of 6-hydroxy-N-(6-hydroxyhexyl)-2,5,7,8-tetramethylchroman-2-carboxamide and 230 mg CAN (0.419 mmol) yielded 40 mg of 2-hydroxy-N-(6-hydroxyhexyl)-2-methyl-4-(2,4,5-trimethyl-3,6-dioxocyclohexa-1,4-dienyl)butanamide as a yellow oil.

¹H NMR (400 MHz, CDCl₃) δ 6.86 (t, 1H), 3.64 (t, 2H), 3.28 (q, 2H), 2.54 (m, 1H), 2.39 (m, 1H), 2.04-1.99 (m, 10H), 1.55 (m, 7H), 1.38 (m, 5H).

Example 32 2-Hydroxy-N-(6-hydroxyhexyl)-2-methyl-4-(2,4,5-trimethyl-3,6-dioxocyclohexa-1,4-dienyl)butanamide

Following the amide coupling procedure described in protocol A, 496 mg 6-hydroxy-2,5,7,8-tetramethylchroman-2-carboxylic acid (1.98 mmol), 376 mg CDI (2.32 mmol) and 404 mg tetrahydrofuranylamine (4.0 mmol) produced 408.0 mg of crude 6-hydroxy-2,5,7,8-tetramethyl-N-((tetrahydrofuran-2-yl)methyl)chroman-2-carboxamide, which was oxidized following protocol B, with 335 mg CAN (0.612 mmol) to yield 74.7 mg of 2-hydroxy-2-methyl-N-((tetrahydrofuran-2-yl)methyl)-4-(2,4,5-trimethyl-3,6-dioxocyclohexa-1,4-dienyl)butanamide as a yellow oil.

¹H NMR (400 MHz, CDCl₃) δ 7.16 (m, 1H), 3.98 (m, 1H), 3.87 (m, 1H), 3.76 (q, 1H), 3.56 (m, 1H), 3.3 (d, 1H), 3.20 (m, 1H), 2.59 (m, 1H), 2.40 (m, 1H), 1.99 (m, 10H), 1.89 (q, 2H), 1.56 (m, 2H), 1.42 (s, 3H).

Example 33 2-Hydroxy-2-methyl-N-(3-morpholinopropyl)-4-(2,4,5-trimethyl-3,6-dioxocyclohexa-1,4-dienyl)butanamide

To a solution of 6-hydroxy-2,5,7,8-tetramethylchroman-2-carboxylic acid (511 mg, 2.1 mmol) in 10 mL THF was added 356 mg CDI and stirred for 2 h. 3-morpholino-propylamine (438 μl, 432 mg, 3.0 mmol) in 10 mL THF was added dropwise and stirred overnight. The reaction was concentrated, dissolved into 70 mL CH₂Cl₂, the organics washed once with 50 mL saturated NaCl solution, dried over Na₂SO₄ and concentrated to brown oil. Flash chromatography yielded 6-hydroxy-2,5,7,8-tetramethyl-N-(3-morpholinopropyl)chroman-2-carboxamide as a pale brown solid.

¹H NMR (400 MHz, CDCl₃) δ 6.57 (br s, 1H), 4.38 (br s, 1H), 3.68 (br s, 4H), 3.64 (m, 1H), 3.21 (m, 1H), 1.57 (m, 2H), 2.42-2.30 (m, 5H), 2.19 (s, 3H), 2.17 (s, 3H), 2.09 (s, 3H), 1.84 (m, 1H), 1.61 (m, 4H), 1.52 (s, 3H). LRMS, APCI, (M⁺+1) 377.

To a solution of 100 mg (0.266 mmol) of 6-hydroxy-2,5,7,8-tetramethyl-N-(3-morpholinopropyl)chroman-2-carboxamide in 5 mL AcCN and one drop of H₂O at 0° C., was added a solution of 320.3 mg CAN (0.584 mmol) in 3 mL H₂O dropwise. The solution was treated with 5 mL EtOAc and 5 mL saturated NaCl followed by ˜1 g of NaHCO₃ and 1 h of vigorous stirring. The suspension was then extracted 3×5 mL 4:1 isopropyl alcohol:isopropyl acetate solution and the combined organics dried over Na₂SO₄, concentrated to a yellow oil and flashed chromatographed to yield 16 mg of 2-hydroxy-2-methyl-N-(3-morpholinopropyl)-4-(2,4,5-trimethyl-3,6-dioxocyclohexa-1,4-dienyl)butanamide as a dark yellow oil.

¹H NMR (400 MHz, CDCl₃) δ 7.75 (t, 1H), 3.74 (m, 4H), 3.36 (m, 2H), 2.53 (m, 4H), 2.40 (dt, 1H), 2.00 (s, 3H), 1.99 (s, 3H), 1.97 (s, 3), 1.95 (m, 1H), 1.75 (m, 2H), 1.58 (m, 1H), 1.39 (s, 3H).

¹³C NMR (100 MHz, CDCl₃) δ 187.6, 187.4, 175.5, 143.3, 140.95, 140.91, 140.2, 75.1, 66.5, 57.6, 53.6, 38.9, 38.6, 27.1, 25.0, 21.1, 12.4, 21.2, 12.0.

Example 34 2-Hydroxy-N-methoxy-N,2-dimethyl-4-(2,4,5-trimethyl-3,6-dioxocyclohexa-1,4-dienyl)butanamide

To a solution of 5.47 g 6-hydroxy-2,5,7,8-tetramethylchroman-2-carboxylic acid (21.9 mmol) in 170 mL THF was added 3.92 g CDI (24.2 mmol) and stirred for 1.25 h at room temperature. To this was added a solution of 2.14 g N,O -dimethylhydroxylamine hydrochloride (21.97 mmol) and 8.2 g N,N-diisopropylethylamine in 50 mL CH₂Cl₂ dropwise over 1 h. The reaction was stirred overnight, concentrated, 250 mL CH₂Cl₂ added and washed sequentially with 100 mL 0.625 M HCl, 100 mL 1.0 M NaHCO₃ and 100 mL saturated NaCl. The organics were dried over Na₂SO₄, concentrated and purified by flash chromatography yielding 4.43 g of 6-hydroxy-N-methoxy-N,2,5,7,8-pentamethylchroman-2-carboxamide as an off-white crystalline solid.

¹H NMR (400 MHz, CDCl₃) δ 3.63 (s, 3H), 3.31 (s, 3H), 2.74-2.55 (m, 3H), 2.18 (s, 3H), 2.16 (s, 3H), 2.08 (s, 3H), 1.73 (m, 1H), 1.59 (s, 3H).

Oxidation as described in protocol B, using 155 mg (0.528 mmol) of 6-hydroxy-N-methoxy-N,2,5,7,8-pentamethylchroman-2-carboxamide and 637 mg CAN (1.16 mmol) yielding 119.4 mg of 2-hydroxy-N-methoxy-N,2-dimethyl-4-(2,4,5-trimethyl-3,6-dioxocyclohexa-1,4-dienyl)butanamide as a yellow solid.

¹H NMR (400 MHz, CDCl₃) δ 3.80 (s, 3H), 3.25 (s, 3H), 2.55 (dt, 1H), 2.37 (dt, 1H), 2.03 (s, 3H), 1.99 (m, 7H), 1.68 (dt, 1H), 1.48 (s, 3H).

Example 35 2-Hydroxy-N,N-bis(2-hydroxyethyl)-2-methyl-4-(2,4,5-trimethyl-3,6-dioxocyclohexa-1,4-dienyl)butanamide

To a solution of 6-hydroxy-2,5,7,8-tetramethylchroman-2-carboxylic acid (500 mg, 2.00 mmol) in 10 mL THF was added 356 mg CDI (2.20 mmol). After stiffing for 1.5 h., a solution of diethanolamine (231 mg, 2.2 mmol) in 10 mL THF was added over 1 h and the reaction was stirred overnight. The reaction was concentrated, dissolved into 70 mL CH₂Cl₂ and washed sequentially with 50 mL 0.62 M HCl, 50 mL 1.0 M NaHCO₃, 50 mL saturated NaCl and dried over Na₂SO₄. The combined aqueous phases were extracted 3×50 mL 3:1 isopropyl alcohol/isopropyl acetate which was dried and concentrated to a brown oil. Flash chromatography yielded 63 mg of 6-hydroxy-N,N-bis(2-hydroxyethyl)-2,5,7,8-tetramethylchroman-2-carboxamide as a yellow oil.

¹H NMR (400 MHz, CDCl₃) δ 4.35 (s, 1H), 4.11 (m, 1H), 3.91 (br m, 1H), 3.81-3.65 (br m, 4H), 3.51 (br s, 2H), 2.71-2.57 (m, 4H), 2.16 (s, 6H), 2.09 (s, 3H), 1.74 (m, 1H).

Oxidation as described in protocol B, using 68.4 mg (0.203 mmol) of precursor 6-hydroxy-N,N-bis(2-hydroxyethyl)-2,5,7,8-tetramethylchroman-2-carboxamide and 244 mg CAN (0.446 mmol) yielding 18.4 mg of 2-hydroxy-N,N-bis(2-hydroxyethyl)-2-methyl-4-(2,4,5-trimethyl-3,6-dioxocyclohexa-1,4-dienyl)butanamide as a yellow oil (25.7%).

¹H NMR (400 MHz, CDCl₃) δ 4.0-3.5 (m, 8H), 2.56 (td, 1H), 2.42 (td, 1H), 2.04 (s, 3H), 2.00 (s, 3H), 1.98 (s, 3H), 1.67 (m, 1H), 1.51 (s, 3H).

Example 36 N-(4-Hydroxyphenethyl)-2-hydroxy-2-methyl-4-(2,4,5-trimethyl-3,6-dioxocyclohexa-1,4-dienyl)butanamide

Following the amide coupling procedure described in protocol A, 500 mg 6-hydroxy-2,5,7,8-tetramethylchroman-2-carboxylic acid (2.0 mmol), 356 mg CDI (2.2 mmol) and 548 mg tyramine (4.0 mmol) produced 537.8 mg of 6-hydroxy-N-(4-hydroxyphenethyl)-2,5,7,8-tetramethylchroman-2-carboxamide as a brown solid.

¹H NMR (400 MHz, d₆-DMSO) δ 9.16 (s, 1H), 7.51 (s, 1H), 7.17 (t, 1H), 6.84 (d, 2H), 6.60 (d, 2H), 3.24 (q, 2H), 2.50 (m), 2.37 (m, 1H), 2.14 (m, 1H), 2.10 (s, 3H), 2.01 (s, 3H), 1.99 (s, 3H), 1.69 (m, 1H), 1.32 (s, 3H).

Oxidation as described in protocol B, using 100 mg 6-hydroxy-N-(4-hydroxyphenethyl)-2,5,7,8-tetramethylchroman-2-carboxamide (0.271 mmol) and 325 mg CAN (0.595 mmol) yielded 15 mg of N-(4-hydroxyphenethyl)-2-hydroxy-2-methyl-4-(2,4,5-trimethyl-3,6-dioxocyclohexa-1,4-dienyl)butanamide as a yellow solid.

¹H NMR (400 MHz, d₄-MeOH) δ 7.75 (t, 1H), 7.00 (d, 2H), 6.63 (d, 2H), 3.34 (m, 2H), 2.68 (t, 2H), 2.54 (m, 1H), 2.12 (m, 1H), 1.93 (s, 6H), 1.90 (s, 3H), 1.78 (td, 1H), 1.48 (m, 1H), 1.28 (s, 3H).

Example 37 N-(2-(Dimethylamino)ethyl)-2-hydroxy-2-methyl-4-(2,4,5-trimethyl-3,6-dioxocyclohexa-1,4-dienyl)butanamide

Following the amide coupling procedure described in protocol A, 1.03 g 6-hydroxy-2,5,7,8-tetramethylchroman-2-carboxylic acid (4.11 mmol), 0.712 g CDI (4.39 mmol) and 704 mg N,N-dimethylethylenediamine (7.99 mmol) produced 1 g of N-(2-(dimethylamino)ethyl)-6-hydroxy-2,5,7,8-tetramethylchroman-2-carboxamide as a white crystalline solid.

¹H NMR (400 MHz, CDCl₃) δ 7.10 (br s, 1H), 4.28 (br s, 1H), 3.22 (m, 2H), 2.60 (m, 2H), 2.33 (m, 2H), 2.23 (m, 6H), 2.09 (s, 9H), 1.89 (m, 1H), 1.52 (s, 3H).

Oxidation as described in protocol B, using 150 mg N-(2-(dimethylamino)-ethyl)-6-hydroxy-2,5,7,8-tetramethylchroman-2-carboxamide (0.468 mmol) and 564 mg CAN (1.03 mmol) with exceptions as noted. The aqueous phase was basified with NaHCO₃ (s), extracted with EtOAc and the combined organics dried with Na₂SO₄, concentrated and flashed yielding 131 mg (83%) of N-(2-(dimethylamino)-ethyl)-2-hydroxy-2-methyl-4-(2,4,5-trimethyl-3,6-dioxocyclohexa-1,4-dienyl)butanamide as a yellow solid.

¹H NMR (400 MHz, CDCl₃) δ 7.62 (t, 1H), 3.48 (q, 2H), 2.63 (m, 3H), 2.37 (s, 6H), 2.30 (td, 1H), 1.96 (m, 10H), 1.57 (m, 1H), 1.41 (s, 3H).

Example 38 N-(2-(Dimethylamino)ethyl)-2-hydroxy-2-methyl-4-(2,4,5-trimethyl-3,6-dioxocyclohexa-1,4-dienyl)butanamide hydrochloride

A solution of 22.8 mg starting quinone in 2 mL MeOH was treated with 20 μL of a 4.0 M HCl in dioxane solution. After five minutes, the yellow solution was concentrated, redissolved in 0.2 mL MeOH and triturated into a large excess of Et₂O, concentrated after one hour and fresh Et₂O added. After 72 h the reaction was filtered and a yellow solid N-(2-(dimethylamino)ethyl)-2-hydroxy-2-methyl-4-(2,4,5-trimethyl-3,6-dioxocyclohexa-1,4-dienyl)butanamide hydrochloride was collected (15.6 mg).

¹H NMR (400 MHz, CDCl₃) δ 9.09 (s, 1H), 5.02 (m, 1H), 4.85 (m, 1H), 4.59 (t, J=5.6 Hz, 2H), 4.09 (s, 6H), 3.94 (td, 1H), 3.67 (td, 1H), 3.26 (s, 3H), 3.23 (s, 6H), 3.07 (td, 1H), 2.91 (td, 1H), 2.64 (s, 3H).

Example 39 N-(2-(Dimethylamino)ethyl)-2-hydroxy-2-methyl-4-(2,4,5-trimethyl-3,6-dioxocyclohexa-1,4-dienyl)butanamide mesylate

N-(2-(dimethylamino)ethyl)-2-hydroxy-2-methyl-4-(2,4,5-trimethyl-3,6-dioxocyclohexa-1,4-dienyl)butanamide (25 mg) was dissolved into 1 mL CH₂Cl₂ and 5.2 μL neat methanesulfonic acid added to the stirred yellow solution. The solution was concentrated, dissolved into CH₂Cl₂ and triturated from Et₂O giving 20 mg of N-(2-(dimethylamino)ethyl)-2-hydroxy-2-methyl-4-(2,4,5-trimethyl-3,6-dioxocyclohexa-1,4-dienyl)butanamide mesylate as a yellow hydroscopic solid.

¹H NMR (400 MHz, CDCl₃) δ 7.9 (t, 1H), 3.87 (m, 1H), 3.56 (m, 1H), 3.32 (m, 1H), 2.96 (s, 3H), 2.95 (s, 3H), 2.80 (s, 3H), 2.65 (td, 1H).

Example 40 N-(3-(dimethylamino)propyl)-2-hydroxy-2-methyl-4-(2,4,5-trimethyl-3,6-dioxocyclohexa-1,4-dienyl)butanamide

N-(3-(dimethylamino)propyl)-2-hydroxy-2-methyl-4-(2,4,5-trimethyl-3,6-dioxocyclohexa-1,4-dienyl)butanamide was prepared following the procedure of Example 37 but substituting N,N-dimethylethylenediamine with N¹,N¹-dimethylpropane-1,3-diamine.

¹H NMR (400 MHz, CDCl₃) δ 7.2 (t, 1H), 3.36 (m, 1H), 3.2-3.3 (m, 3H), 2.93 (s, 6H), 2.6 (m, 1H), 2.35 (m, 1H), 2.06 (m, 2H), 2.00 (s, 3H), 1.98 (s, 3H), 1.95 (s, 3H), 1.82 (td, 1H), 1.62 (td, 1H), 1.43 (s, 3H).

Example 41 6,6′-(4,4′-(piperazine-1,4-diyl)bis(3-hydroxy-3-methyl-4-oxobutane-4,1-diyl))bis(2,3,5-trimethylcyclohexa-2,5-diene-1,4-dione)

A solution of 6-hydroxy-2,5,7,8-tetramethylchroman-2-carboxylic acid (5.0 g, 20 mmol), pyridine (50 mL), and acetic anhydride (43 mL) were stirred for 5 h. Water was added and the mixture extracted into methyl t-butyl ether (MTBE) (2×100 mL) and the combined organics washed with water (2×200 mL), copper sulfate solution (2×200 mL), and finally brine (2×50 mL). The organic layer was collected, dried over sodium sulfate and de-colorized using activated charcoal and concentrated to a light green foam. The crude material was redissolved in CH₂Cl₂ (50 mL) and dimethylformamide (2 drops) followed by oxalyl chloride (1.9 mL) added dropwise. Immediate evolution of gas was observed. The mixture was stirred open to the air for 2 h and the solvent removed to give 2-(chlorocarbonyl)-2,5,7,8-tetramethylchroman-6-yl acetate (3.9 g, 13 mmol), which was used without further purification.

2-(chlorocarbonyl)-2,5,7,8-tetramethylchroman-6-yl acetate (3.9 g, 13 mmol) in CH₂Cl₂ (25 mL) was treated with di-isopropylethylamine (DIEA) (5.0 mL) followed by piperazine (0.48 g, 5.6 mmol). The reaction mixture was auto-refluxed briefly upon piperazine addition. The reaction was allowed to cool to ambient temperature and stirred for 16 h. The mixture was then poured into MTBE (100 mL), the organic layer removed and washed with saturated ammonium chloride solution (3×50 mL) then dried over sodium sulfate. Solvent was removed to provide 2,2′-(piperazine-1,4-diylbis(oxomethylene))bis(2,5,7,8-tetramethyl-3,4,5,8-tetrahydro-2H-chromene-6,2-diyl) diacetate (3.7 g, 5.8 mmol) as an amorphous off-white solid, which was used directly without further purification.

To a solution of 2,2′-(piperazine-1,4-diylbis(oxomethylene))bis(2,5,7,8-tetramethyl-3,4,5,8-tetrahydro-2H-chromene-6,2-diyl) diacetate (2.36 g), THF (25 mL) and MeOH (10 mL) was added KOH (1.04 g as a solution in 10 mL MeOH). The reaction mixture was stirred at ambient temperature for 16 h, after which time it was fully dissolved. To the stirred reaction mixture was then added CAN (9.16 g, 16.7 mmol) as a solution in water (50 mL). After 1 h, addition water was added (50 mL), causing the formation of a beige precipitate. The supernatant was decanted, and extracted with MTBE. Solvent was removed under vacuum to give a crude yellow product, which was purified by flash chromatography, eluting with EtOAc/hexane (30% to 100%) to provide 6,6′-(4,4′-(piperazine-1,4-diyl)bis(3-hydroxy-3-methyl-4-oxobutane-4,1-diyl))bis(2,3,5-trimethylcyclohexa-2,5-diene-1,4-dione) as a hard amorphous yellow solid.

¹H NMR (400 MHz, CDCl₃) δ 5.50 (br s, 2H), 3.95 (br s, 4H), 2.50-3.28 (br m, 6H), 2.50-2.40 (m, 4H), 2.02-1.90 (m, 18H), 1.75 (br m, 2H), 1.59 (br m, 2H), 1.36 (s, 6H).

Example 42 2-(3-Hydroxy-3-methyl-4-oxo-4-(piperidin-1-yl)butyl)-3,5,6-trimethylcyclohexa-2,5-diene-1,4-dione

6-Hydroxy-2,5,7,8-tetramethylchroman-2-carboxylic acid (1.005 g, 4.00 mmol) in 22 mL THF was treated with 722.8 mg CDI (4.4 mmol) and stirred for 2 h at room temperature. The pale yellow solution was then treated with 450 μL (381 mg, 4.47 mmol) piperidine in 22 mL THF in 1-2 mL portions over 2 h. The reaction was stirred overnight at room temperature. The reaction was concentrated and the residue dissolved in 100 mL CH₂Cl₂ and sequentially washed with 50 mL 0.25 M HCl, 50 mL 1.0 M NaHCO₃, 50 mL saturated NaCl and dried over Na₂SO₄. The organic phase was concentrated. Flash chromatography yielded 992 mg of (6-hydroxy-2,5,7,8-tetramethylchroman-2-yl)(piperidin-1-yl)methanone as an off-white solid.

¹H NMR (400 MHz, CDCl₃) δ 4.42 (s, 1H), 3.95-3.83 (br m, 2H), 3.46 (br s, 2H), 2.77 (m, 1H), 2.63-2.52 (m, 2H), 2.16 (s, 3H), 2.15 (s, 3H), 2.08 (S, 3H), 1.70 (m, 1H), 1.58-1.48 (m, 2H), 1.45-1.36 (br s, 2H).

A solution of 319 mg of (6-hydroxy-2,5,7,8-tetramethylchroman-2-yl)(piperidin-1-yl)methanone (1.02 mmol) in 5 mL MTBE which was treated with 1.077 g FeCl₃.6H₂O in 6 mL H₂O. The reaction mixture rapidly turned black which faded to a yellow color over the course of the reaction. An additional 2 mL MTBE was added and stirred vigorously for 3 h at room temp. The reaction was quenched with 10 mL H₂O and 10 mL MTBE, the layers separated and the organics washed with H₂O until colorless. The combined aqueous phases were extracted 2×10 mL MTBE and the combined organics washed with saturated NaCl and dried over Na₂SO₄. Flash chromatography yielded 335 mg of 2-(3-hydroxy-3-methyl-4-oxo-4-(piperidin-1-yl)butyl)-3,5,6-trimethylcyclohexa-2,5-diene-1,4-dione as a dark yellow oil.

¹H NMR (400 MHz, CDCl₃) δ 5.14 (s, 1H), 3.65-3.45 (br m, 4H), 2.48 (td, 1H), 2.36 (dt, 1H), 1.97 (s, 3H), 1.94 (s, 6H), 1.88 (m, 1H), 1.68-1.57 (m, 7H), 1.42 (s, 3H).

¹³C NMR (100 MHz, CDCl₃) δ 187.4, 187.1, 173.4, 143.4, 140.6, 140.5, 140.1, 73.3, 38.9, 26.2, 25.9, 24.3, 21.3, 12.3, 12.2, 11.8.

Example 43 N-Hexyl-6-hydroxy-2,5,7,8-tetramethylchroman-2-carboxamide

6-Hydroxy-2,5,7,8-tetramethylchroman-2-carboxylic acid (5.0 g, 19.99 mmol) was dissolved in pyridine (18 mL) and Ac₂O added (10 mL) in one portion. The exothermic reaction warmed to 40° C., was let cool to room temperature and stirred overnight. The crude reaction mixture was quenched with 100 mL H₂O, stirred for 1 h followed by additional 100 mL H₂O and 1 h of stirring. A fine white precipitate of 6-acetoxy-2,5,7,8-tetramethylchroman-2-carboxylic acid was formed and collected by filtration (4.544 g).

Crude 6-acetoxy-2,5,7,8-tetramethylchroman-2-carboxylic acid was dissolved in 30 mL CH₂Cl₂, 2 drops of DMF added followed by slow addition of 1.5 mL oxalyl chloride. Gas evolved for 1 h and the solution was stirred overnight at room temperature. The reaction mixture was concentrated separated into five equal aliquots of 2-(chlorocarbonyl)-2,5,7,8-tetramethylchroman-6-yl acetate.

To one of the above aliquots of crude 2-(chlorocarbonyl)-2,5,7,8-tetramethylchroman-6-yl acetate in 10 mL CH₂Cl₂ was added 1.0 mL diisopropylethylamine followed by 315 mg 1-hexylamine and overnight stiffing. The reaction mixture was poured into 1.0 M citric acid and 50 mL EtOAc added. The organic layer was separated and purified by flash chromatography to give 781 mg of 2-(hexylcarbamoyl)-2,5,7,8-tetramethylchroman-6-yl acetate, as a clear syrup. MS (m/z): M⁺376.3

Crude 2-(hexylcarbamoyl)-2,5,7,8-tetramethylchroman-6-yl acetate (187 mg, 0.25 mmol) in 1.25 mL MeOH was treated with 33.7 mg (0.625 mmol) NaOMe and let stir overnight. The stirred brown solution then was diluted with water (10 mL), neutralized with 2.5 M HCl (1.5 mL) and 10 mL EtOAc added. The layers were separated and the organics dried over Na₂SO₄ and concentrated. Flash chromatography yielded 90 mg of N-hexyl-6-hydroxy-2,5,7,8-tetramethylchroman-2-carboxamide.

¹H NMR (400 MHz, CDCl₃) δ 6.46 (t, 1H), 4.76 (s, 1H), 3.20 (m, 2H), 2.58 (m, 3H), 2.18 (s, 6H), 2.09 (s, 3H), 1.88 (m, 1H), 1.51 (s, 3H), 1.38 (m, 2H), 1.25-1.11 (m, 6H), 0.85 (t, 3H).

A solution of 75 mg of N-hexyl-6-hydroxy-2,5,7,8-tetramethylchroman-2-carboxamide (0.225 mmol) in 2 mL MTBE was treated with 2.0 mL of 0.5 M FeCl₃.6H₂O and stirred vigorously for 24 h. The solution was treated with 5 mL H₂O and 10 mL MTBE, the layers were separated and the organics washed with 2×5 mL H₂O, 2×5 mL saturated NaCl. The combined organics were dried over Na₂SO₄ and concentrated. Flash chromatography yielded N-hexyl-6-hydroxy-2,5,7,8-tetramethylchroman-2-carboxamide as an orange-brown oil which was rechromatographed to yield 31 mg of a bright yellow oil.

¹H NMR (400 MHz, CDCl₃) δ 6.82 (t, 1H), 3.48 (s, 1H), 3.22 (q, 2H), 2.55 (m, 1H), 2.36 (m, 1H), 2.04-1.96 (m, 10H), 1.61-1.46 (m, 3H), 1.38 (s, 3H), 1.33-1.22 (m, 6H), 0.84 (t, 3H).

Biological Examples Example A Screening Compounds of the Invention in Human Dermal Fibroblasts from Friedreich's Ataxia Patients

An initial screen was performed to identify compounds effective for the amelioration of redox disorders. Test samples, 4 reference compounds (idebenone, decylubiquinone, Trolox and α-tocopherol acetate), and solvent controls were tested for their ability to rescue FRDA fibroblasts stressed by addition of L-buthionine-(S,R)-sulfoximine (BSO), as described in Jauslin et al., Hum. Mol. Genet. 11(24):3055 (2002), Jauslin et al., FASEB J. 17:1972-4 (2003), and International Patent Application WO 2004/003565. Human dermal fibroblasts from Friedreich's Ataxia patients have been shown to be hypersensitive to inhibition of the de novo synthesis of glutathione (GSH) with L-buthionine-(S,R)-sulfoximine (BSO), a specific inhibitor of GSH synthetase (Jauslin et al., Hum. Mol. Genet. 11(24):3055 (2002)). This specific BSO-mediated cell death can be prevented by administration of antioxidants or molecules involved in the antioxidant pathway, such as α-tocopherol, selenium, or small molecule glutathione peroxidase mimetics. However, antioxidants differ in their potency, i.e. the concentration at which they are able to rescue BSO-stressed FRDA fibroblasts.

MEM (a medium enriched in amino acids and vitamins, catalog no. 1-31F24-I) and Medium 199 (M199, catalog no. 1-21F22-I) with Earle's Balanced Salts, without phenol red, were purchased from Bioconcept. Fetal Calf Serum was obtained from PAA Laboratories. Basic fibroblast growth factor and epidermal growth factor were purchased from PeproTech. Penicillin-streptomycin-glutamine mix, L-buthionine (S,R)-sulfoximine, (+)-α-tocopherol acetate, decylubiquinone, and insulin from bovine pancreas were purchased from Sigma. Trolox (6-Hydroxy-2,5,7,8-tetramethylchromane-2-carboxylic acid) was obtained from Fluka. Idebenone was obtained from Chemo Iberica. Calcein AM was purchased from Molecular Probes. Cell culture medium was made by combining 125 ml M199 EBS, 50 ml Fetal Calf Serum, 100 U/ml penicillin, 100 μg/ml streptomycin, 2 mM glutamine, 10 μg/ml insulin, 10 ng/ml EGF, and 10 ng/ml bFGF; MEM EBS was added to make the volume up to 500 ml. A 10 mM BSO solution was prepared by dissolving 444 mg BSO in 200 ml of medium with subsequent filter-sterilization. During the course of the experiments, this solution was stored at +4° C. The cells were obtained from the Coriell Cell Repositories (Camden, N.J.; repository number GM04078) and grown in 10 cm tissue culture plates. Every third day, they were split at a 1:3 ratio.

The test samples were supplied in 1.5 ml glass vials. The compounds were diluted with DMSO, ethanol or PBS to result in a 5 mM stock solution. Once dissolved, they were stored at −20° C. Reference antioxidants (idebenone, decylubiquinone, α-tocopherol acetate and trolox) were dissolved in DMSO.

Test samples were screened according to the following protocol: A culture with FRDA fibroblasts was started from a 1 ml vial with approximately 500,000 cells stored in liquid nitrogen. Cells were propagated in 10 cm cell culture dishes by splitting every third day in a ratio of 1:3 until nine plates were available. Once confluent, fibroblasts were harvested. For 54 micro titer plates (96 well-MTP) a total of 14.3 million cells (passage eight) were re-suspended in 480 ml medium, corresponding to 100 μl medium with 3,000 cells/well. The remaining cells were distributed in 10 cm cell culture plates (500,000 cells/plate) for propagation. The plates were incubated overnight at 37° C. in a atmosphere with 95% humidity and 5% CO₂ to allow attachment of the cells to the culture plate.

MTP medium (243 μl) was added to a well of the microtiter plate. The test compounds were unfrozen, and 7.5 μl of a 5 mM stock solution was dissolved in the well containing 243 μl medium, resulting in a 150 μM master solution. Serial dilutions from the master solution were made. The period between the single dilution steps was kept as short as possible (generally less than 1 second).

Plates were kept overnight in the cell culture incubator. The next day, 10 of a 10 mM BSO solution were added to the wells, resulting in a 1 mM final BSO concentration. Forty-eight hours later, three plates were examined under a phase-contrast microscope to verify that the cells in the 0% control (wells E1-H1) were clearly dead. The medium from all plates was discarded, and the remaining liquid was removed by gently tapping the plate inversed onto a paper towel.

100 μl of PBS containing 1.2 μM Calcein AM were then added to each well. The plates were incubated for 50-70 minutes at room temperature. After that time the PBS was discarded, the plate gently tapped on a paper towel and fluorescence (excitation/emission wavelengths of 485 nm and 525 nm, respectively) was read on a Gemini fluorescence reader. Data was imported into Microsoft Excel (EXCEL is a registered trademark of Microsoft Corporation for a spreadsheet program) and used to calculate the EC₅₀ concentration for each compound.

The compounds were tested three times, i.e., the experiment was performed three times, the passage number of the cells increasing by one with every repetition.

The solvents (DMSO, ethanol, PBS) neither had a detrimental effect on the viability of non-BSO treated cells nor did they have a beneficial influence on BSO-treated fibroblasts even at the highest concentration tested (1%). None of the compounds showed auto-fluorescence. The viability of non-BSO treated fibroblasts was set as 100%, and the viability of the BSO- and compound-treated cells was calculated as relative to this value.

The following table summarizes the EC₅₀ for the four control compounds.

EC₅₀ [μM] Compound Value 1 Value 2 Value 3 Average Stdev decylubiquinone 0.05 0.035 0.03 0.038 0.010 alpha-tocopherol acetate 0.4 0.15 0.35 0.30 0.13 Idebenone 1.5 1 1 1.2 0.3 Trolox 9 9 8 8.7 0.6

Certain compounds of the present invention such as:

-   2-hydroxy-N-(2-hydroxyethyl)-2-methyl-4-(2,4,5-trimethyl-3,6-dioxocyclohexa-1,4-dienyl)butanamide; -   2-hydroxy-N-(3-hydroxypropyl)-2-methyl-4-(2,4,5-trimethyl-3,6-dioxocyclohexa-1,4-dienyl)butanamide; -   2-(3-hydroxy-4-(4-hydroxypiperidin-1-yl)-3-methyl-4-oxobutyl)-3,5,6-trimethylcyclohexa-2,5-diene-1,4-dione; -   2-hydroxy-2-methyl-4-(2,4,5-trimethyl-3,6-dioxocyclohexa-1,4-dienyl)butanamide; -   2-hydroxy-N-(4-hydroxybutyl)-2-methyl-4-(2,4,5-trimethyl-3,6-dioxocyclohexa-1,4-dienyl)butanamide; -   2-hydroxy-N-(5-hydroxypentyl)-2-methyl-4-(2,4,5-trimethyl-3,6-dioxocyclohexa-1,4-dienyl)butanamide; -   2-hydroxy-N-(1-hydroxypropan-2-yl)-2-methyl-4-(2,4,5-trimethyl-3,6-dioxocyclohexa-1,4-dienyl)butanamide;     (R)-2-hydroxy-N-(2-hydroxyethyl)-2-methyl-4-(2,4,5-trimethyl-3,6-dioxocyclohexa-1,4-dienyl)butanamide; -   (S)-2-hydroxy-N-(2-hydroxyethyl)-2-methyl-4-(2,4,5-trimethyl-3,6-dioxocyclohexa-1,4-dienyl)butanamide; -   N-(3-(1H-imidazol-1-yl)propyl)-2-hydroxy-2-methyl-4-(2,4,5-trimethyl-3,6-dioxocyclohexa-1,4-dienyl)butanamide; -   2-hydroxy-N-(2-(2-hydroxyethoxy)ethyl)-2-methyl-4-(2,4,5-trimethyl-3,6-dioxocyclohexa-1,4-dienyl)butanamide; -   2-hydroxy-N-(2-hydroxypropyl)-2-methyl-4-(2,4,5-trimethyl-3,6-dioxocyclohexa-1,4-dienyl)butanamide; -   2-(3-hydroxy-3-methyl-4-(4-methylpiperazin-1-yl)-4-oxobutyl)-3,5,6-trimethylcyclohexa-2,5-diene-1,4-dione; -   2-(4-(4-benzylpiperazin-1-yl)-3-hydroxy-3-methyl-4-oxobutyl)-3,5,6-trimethylcyclohexa-2,5-diene-1,4-dione; -   2-hydroxy-2-methyl-N-(3-morpholinopropyl)-4-(2,4,5-trimethyl-3,6-dioxocyclohexa-1,4-dienyl)butanamide; -   2-hydroxy-N,N-bis(2-hydroxyethyl)-2-methyl-4-(2,4,5-trimethyl-3,6-dioxocyclohexa-1,4-dienyl)butanamide; -   N-(2-(dimethylamino)ethyl)-2-hydroxy-2-methyl-4-(2,4,5-trimethyl-3,6-dioxocyclohexa-1,4-dienyl)butanamide; -   2-hydroxy-N-(4-hydroxyphenethyl)-2-methyl-4-(2,4,5-trimethyl-3,6-dioxocyclohexa-1,4-dienyl)butanamide; -   6,6′-(4,4′-(piperazine-1,4-diyl)bis(3-hydroxy-3-methyl-4-oxobutane-4,1-diyl))bis(2,3,5-trimethylcyclohexa-2,5-diene-1,4-dione); -   N-(3-(dimethylamino)propyl)-2-hydroxy-2-methyl-4-(2,4,5-trimethyl-3,6-dioxocyclohexa-1,4-dienyl)butanamide; -   2-(4-(4-acetylpiperazin-1-yl)-3-hydroxy-3-methyl-4-oxobutyl)-3,5,6-trimethylcyclohexa-2,5-diene-1,4-dione; -   2-(3-hydroxy-3-methyl-4-oxo-4-(piperazin-1-yl)butyl)-3,5,6-trimethylcyclohexa-2,5-diene-1,4-dione; -   (R)-2-hydroxy-2-methyl-4-(2,4,5-trimethyl-3,6-dioxocyclohexa-1,4-dienyl)butanamide; -   (S)-2-hydroxy-2-methyl-4-(2,4,5-trimethyl-3,6-dioxocyclohexa-1,4-dienyl)butanamide; -   (R)-2-(4-(4-acetylpiperazin-1-yl)-3-hydroxy-3-methyl-4-oxobutyl)-3,5,6-trimethylcyclohexa-2,5-diene-1,4-dione; -   (S)-2-(4-(4-acetylpiperazin-1-yl)-3-hydroxy-3-methyl-4-oxobutyl)-3,5,6-trimethylcyclohexa-2,5-diene-1,4-dione; -   (R)-2-(3-hydroxy-4-(4-hydroxypiperidin-1-yl)-3-methyl-4-oxobutyl)-3,5,6-trimethylcyclohexa-2,5-diene-1,4-dione; -   (S)-2-(3-hydroxy-4-(4-hydroxypiperidin-1-yl)-3-methyl-4-oxobutyl)-3,5,6-trimethylcyclohexa-2,5-diene-1,4-dione; -   N-(2-fluorophenethyl)-2-hydroxy-2-methyl-4-(2,4,5-trimethyl-3,6-dioxocyclohexa-1,4-dienyl)butanamide; -   N-(3-fluorophenethyl)-2-hydroxy-2-methyl-4-(2,4,5-trimethyl-3,6-dioxocyclohexa-1,4-dienyl)butanamide; -   N-(4-fluorophenethyl)-2-hydroxy-2-methyl-4-(2,4,5-trimethyl-3,6-dioxocyclohexa-1,4-dienyl)butanamide; -   N-(2-chlorophenethyl)-2-hydroxy-2-methyl-4-(2,4,5-trimethyl-3,6-dioxocyclohexa-1,4-dienyl)butanamide; -   N-(3-chlorophenethyl)-2-hydroxy-2-methyl-4-(2,4,5-trimethyl-3,6-dioxocyclohexa-1,4-dienyl)butanamide; -   N-(4-chlorophenethyl)-2-hydroxy-2-methyl-4-(2,4,5-trimethyl-3,6-dioxocyclohexa-1,4-dienyl)butanamide; -   2-hydroxy-N-(4-methoxyphenyl)-2-methyl-4-(2,4,5-trimethyl-3,6-dioxocyclohexa-1,4-dienyl)butanamide; -   N-(4-fluorophenyl)-2-hydroxy-2-methyl-4-(2,4,5-trimethyl-3,6-dioxocyclohexa-1,4-dienyl)butanamide; -   N-(4-chlorophenyl)-2-hydroxy-2-methyl-4-(2,4,5-trimethyl-3,6-dioxocyclohexa-1,4-dienyl)butanamide; -   N-(2-fluorobenzyl)-2-hydroxy-2-methyl-4-(2,4,5-trimethyl-3,6-dioxocyclohexa-1,4-dienyl)butanamide; -   N-(3-fluorobenzyl)-2-hydroxy-2-methyl-4-(2,4,5-trimethyl-3,6-dioxocyclohexa-1,4-dienyl)butanamide; -   N-(4-fluorobenzyl)-2-hydroxy-2-methyl-4-(2,4,5-trimethyl-3,6-dioxocyclohexa-1,4-dienyl)butanamide; -   N-(2-chlorobenzyl)-2-hydroxy-2-methyl-4-(2,4,5-trimethyl-3,6-dioxocyclohexa-1,4-dienyl)butanamide; -   N-(3-chlorobenzyl)-2-hydroxy-2-methyl-4-(2,4,5-trimethyl-3,6-dioxocyclohexa-1,4-dienyl)butanamide; -   N-(4-chlorobenzyl)-2-hydroxy-2-methyl-4-(2,4,5-trimethyl-3,6-dioxocyclohexa-1,4-dienyl)butanamide;     exhibited protection against FRDA with an EC₅₀ of less than about     100 nM.

Example B Screening Compounds of the Invention in Fibroblasts from Huntington's Patients

Compounds of the invention were tested using the screen as described in Example A, but substituting FRDA cells with Huntington's cells obtained from the Coriell Cell Repositories (Camden, N.J.; repository number GM 04281). The compounds were tested for their ability to rescue human dermal fibroblasts from Huntington's patients from oxidative stress.

Certain compounds of the present invention such as:

-   2-hydroxy-N-(2-hydroxyethyl)-2-methyl-4-(2,4,5-trimethyl-3,6-dioxocyclohexa-1,4-dienyl)butanamide; -   2-hydroxy-N-(3-hydroxypropyl)-2-methyl-4-(2,4,5-trimethyl-3,6-dioxocyclohexa-1,4-dienyl)butanamide; -   2-hydroxy-2-methyl-4-(2,4,5-trimethyl-3,6-dioxocyclohexa-1,4-dienyl)butanamide; -   2-hydroxy-N-(4-hydroxybutyl)-2-methyl-4-(2,4,5-trimethyl-3,6-dioxocyclohexa-1,4-dienyl)butanamide; -   2-hydroxy-N-(5-hydroxypentyl)-2-methyl-4-(2,4,5-trimethyl-3,6-dioxocyclohexa-1,4-dienyl)butanamide; -   2-hydroxy-N-(1-hydroxypropan-2-yl)-2-methyl-4-(2,4,5-trimethyl-3,6-dioxocyclohexa-1,4-dienyl)butanamide; -   (R)-2-hydroxy-N-(2-hydroxyethyl)-2-methyl-4-(2,4,5-trimethyl-3,6-dioxocyclohexa-1,4-dienyl)butanamide; -   (S)-2-hydroxy-N-(2-hydroxyethyl)-2-methyl-4-(2,4,5-trimethyl-3,6-dioxocyclohexa-1,4-dienyl)butanamide; -   N-(3-(1H-imidazol-1-yl)propyl)-2-hydroxy-2-methyl-4-(2,4,5-trimethyl-3,6-dioxocyclohexa-1,4-dienyl)butanamide; -   2-hydroxy-N-(2-(2-hydroxyethoxy)ethyl)-2-methyl-4-(2,4,5-trimethyl-3,6-dioxocyclohexa-1,4-dienyl)butanamide; -   2-hydroxy-2-methyl-N-(3-(2-oxopyrrolidin-1-yl)propyl)-4-(2,4,5-trimethyl-3,6-dioxocyclohexa-1,4-dienyl)butanamide; -   2-hydroxy-N-(2-hydroxypropyl)-2-methyl-4-(2,4,5-trimethyl-3,6-dioxocyclohexa-1,4-dienyl)butanamide; -   2-(3-hydroxy-3-methyl-4-(4-methylpiperazin-1-yl)-4-oxobutyl)-3,5,6-trimethylcyclohexa-2,5-diene-1,4-dione; -   2-(4-(4-benzylpiperazin-1-yl)-3-hydroxy-3-methyl-4-oxobutyl)-3,5,6-trimethylcyclohexa-2,5-diene-1,4-dione; -   2-hydroxy-2-methyl-N-(3-morpholinopropyl)-4-(2,4,5-trimethyl-3,6-dioxocyclohexa-1,4-dienyl)butanamide; -   2-hydroxy-N,N-bis(2-hydroxyethyl)-2-methyl-4-(2,4,5-trimethyl-3,6-dioxocyclohexa-1,4-dienyl)butanamide; -   N-(2-(dimethylamino)ethyl)-2-hydroxy-2-methyl-4-(2,4,5-trimethyl-3,6-dioxocyclohexa-1,4-dienyl)butanamide; -   2-hydroxy-N-(4-hydroxyphenethyl)-2-methyl-4-(2,4,5-trimethyl-3,6-dioxocyclohexa-1,4-dienyl)butanamide; -   6,6′-(4,4′-(piperazine-1,4-diyl)bis(3-hydroxy-3-methyl-4-oxobutane-4,1-diyl))bis(2,3,5-trimethylcyclohexa-2,5-diene-1,4-dione); -   N-(3-(dimethylamino)propyl)-2-hydroxy-2-methyl-4-(2,4,5-trimethyl-3,6-dioxocyclohexa-1,4-dienyl)butanamide; -   2-(4-(4-acetylpiperazin-1-yl)-3-hydroxy-3-methyl-4-oxobutyl)-3,5,6-trimethylcyclohexa-2,5-diene-1,4-dione; -   (R)-2-hydroxy-2-methyl-4-(2,4,5-trimethyl-3,6-dioxocyclohexa-1,4-dienyl)butanamide; -   (S)-2-hydroxy-2-methyl-4-(2,4,5-trimethyl-3,6-dioxocyclohexa-1,4-dienyl)butanamide; -   (R)-2-(4-(4-acetylpiperazin-1-yl)-3-hydroxy-3-methyl-4-oxobutyl)-3,5,6-trimethylcyclohexa-2,5-diene-1,4-dione; -   (S)-2-(4-(4-acetylpiperazin-1-yl)-3-hydroxy-3-methyl-4-oxobutyl)-3,5,6-trimethylcyclohexa-2,5-diene-1,4-dione; -   N-(4-fluorophenethyl)-2-hydroxy-2-methyl-4-(2,4,5-trimethyl-3,6-dioxocyclohexa-1,4-dienyl)butanamide; -   N-(3-chlorophenethyl)-2-hydroxy-2-methyl-4-(2,4,5-trimethyl-3,6-dioxocyclohexa-1,4-dienyl)butanamide; -   N-(4-chlorophenethyl)-2-hydroxy-2-methyl-4-(2,4,5-trimethyl-3,6-dioxocyclohexa-1,4-dienyl)butanamide; -   2-hydroxy-N-(4-methoxyphenyl)-2-methyl-4-(2,4,5-trimethyl-3,6-dioxocyclohexa-1,4-dienyl)butanamide; -   N-(4-fluorophenyl)-2-hydroxy-2-methyl-4-(2,4,5-trimethyl-3,6-dioxocyclohexa-1,4-dienyl)butanamide; -   N-(4-chlorophenyl)-2-hydroxy-2-methyl-4-(2,4,5-trimethyl-3,6-dioxocyclohexa-1,4-dienyl)butanamide; -   N-(2-fluorobenzyl)-2-hydroxy-2-methyl-4-(2,4,5-trimethyl-3,6-dioxocyclohexa-1,4-dienyl)butanamide; -   N-(3-fluorobenzyl)-2-hydroxy-2-methyl-4-(2,4,5-trimethyl-3,6-dioxocyclohexa-1,4-dienyl)butanamide; -   N-(4-fluorobenzyl)-2-hydroxy-2-methyl-4-(2,4,5-trimethyl-3,6-dioxocyclohexa-1,4-dienyl)butanamide; -   N-(2-chlorobenzyl)-2-hydroxy-2-methyl-4-(2,4,5-trimethyl-3,6-dioxocyclohexa-1,4-dienyl)butanamide; -   N-(3-chlorobenzyl)-2-hydroxy-2-methyl-4-(2,4,5-trimethyl-3,6-dioxocyclohexa-1,4-dienyl)butanamide; -   N-(4-chlorobenzyl)-2-hydroxy-2-methyl-4-(2,4,5-trimethyl-3,6-dioxocyclohexa-1,4-dienyl)butanamide;     exhibited protection against Hungtington's with an EC₅₀ of less than     about 100 nM.

Example C Screening Compounds of the Invention in Fibroblasts from Leber's Hereditary Optic Neuropathy Patients

Compounds of the invention were screened as described in Example A, but substituting FRDA cells with Leber's Hereditary Optic Neuropathy (LHON) cells obtained from the Coriell Cell Repositories (Camden, N.J.; repository number GM03858). The compounds were tested for their ability to rescue human dermal fibroblasts from LHON patients from oxidative stress.

Certain compounds of the present invention such as:

-   2-hydroxy-N-(2-hydroxyethyl)-2-methyl-4-(2,4,5-trimethyl-3,6-dioxocyclohexa-1,4-dienyl)butanamide; -   2-(3-hydroxy-3-methyl-4-oxo-4-(piperidin-1-yl)butyl)-3,5,6-trimethylcyclohexa-2,5-diene-1,4-dione; -   2-(4-(azepan-1-yl)-3-hydroxy-3-methyl-4-oxobutyl)-3,5,6-trimethylcyclohexa-2,5-diene-1,4-dione; -   N-hexyl-2-hydroxy-2-methyl-4-(2,4,5-trimethyl-3,6-dioxocyclohexa-1,4-dienyl)butanamide; -   N-benzyl-2-hydroxy-2-methyl-4-(2,4,5-trimethyl-3,6-dioxocyclohexa-1,4-dienyl)butanamide; -   2-hydroxy-N-(3-hydroxypropyl)-2-methyl-4-(2,4,5-trimethyl-3,6-dioxocyclohexa-1,4-dienyl)butanamide; -   2-hydroxy-N-isopentyl-2-methyl-4-(2,4,5-trimethyl-3,6-dioxocyclohexa-1,4-dienyl)butanamide; -   2-hydroxy-2-methyl-4-(2,4,5-trimethyl-3,6-dioxocyclohexa-1,4-dienyl)butanamide; -   2-hydroxy-N-(4-hydroxybutyl)-2-methyl-4-(2,4,5-trimethyl-3,6-dioxocyclohexa-1,4-dienyl)butanamide; -   2-hydroxy-N-(5-hydroxypentyl)-2-methyl-4-(2,4,5-trimethyl-3,6-dioxocyclohexa-1,4-dienyl)butanamide; -   2-hydroxy-N-(1-hydroxypropan-2-yl)-2-methyl-4-(2,4,5-trimethyl-3,6-dioxocyclohexa-1,4-dienyl)butanamide; -   2-hydroxy-N-(2-(2-hydroxyethoxy)ethyl)-2-methyl-4-(2,4,5-trimethyl-3,6-dioxocyclohexa-1,4-dienyl)butanamide; -   2-hydroxy-N-(2-hydroxypropyl)-2-methyl-4-(2,4,5-trimethyl-3,6-dioxocyclohexa-1,4-dienyl)butanamide; -   2-(4-(4-benzylpiperazin-1-yl)-3-hydroxy-3-methyl-4-oxobutyl)-3,5,6-trimethylcyclohexa-2,5-diene-1,4-dione; -   N-(2-(dimethylamino)ethyl)-2-hydroxy-2-methyl-4-(2,4,5-trimethyl-3,6-dioxocyclohexa-1,4-dienyl)butanamide; -   2-hydroxy-N-(4-hydroxyphenethyl)-2-methyl-4-(2,4,5-trimethyl-3,6-dioxocyclohexa-1,4-dienyl)butanamide; -   6,6′-(4,4′-(piperazine-1,4-diyl)bis(3-hydroxy-3-methyl-4-oxobutane-4,1-diyl))bis(2,3,5-trimethylcyclohexa-2,5-diene-1,4-dione); -   2-hydroxy-2-methyl-N-(pyridin-4-ylmethyl)-4-(2,4,5-trimethyl-3,6-dioxocyclohexa-1,4-dienyl)butanamide; -   2-hydroxy-2-methyl-N-(pyridin-3-ylmethyl)-4-(2,4,5-trimethyl-3,6-dioxocyclohexa-1,4-dienyl)butanamide; -   2-hydroxy-2-methyl-N-(3-(methylsulfonyl)propyl)-4-(2,4,5-trimethyl-3,6-dioxocyclohexa-1,4-dienyl)butanamide; -   2-(4-(4-acetylpiperazin-1-yl)-3-hydroxy-3-methyl-4-oxobutyl)-3,5,6-trimethylcyclohexa-2,5-diene-1,4-dione; -   2-(4-(4,4-difluoropiperidin-1-yl)-3-hydroxy-3-methyl-4-oxobutyl)-3,5,6-trimethylcyclohexa-2,5-diene-1,4-dione; -   2-(4-(4-benzoylpiperazin-1-yl)-3-hydroxy-3-methyl-4-oxobutyl)-3,5,6-trimethylcyclohexa-2,5-diene-1,4-dione; -   (R)-2-hydroxy-2-methyl-4-(2,4,5-trimethyl-3,6-dioxocyclohexa-1,4-dienyl)butanamide; -   (S)-2-hydroxy-2-methyl-4-(2,4,5-trimethyl-3,6-dioxocyclohexa-1,4-dienyl)butanamide; -   (R)-2-(4-(4-acetylpiperazin-1-yl)-3-hydroxy-3-methyl-4-oxobutyl)-3,5,6-trimethylcyclohexa-2,5-diene-1,4-dione; -   (S)-2-(4-(4-acetylpiperazin-1-yl)-3-hydroxy-3-methyl-4-oxobutyl)-3,5,6-trimethylcyclohexa-2,5-diene-1,4-dione; -   (R)-2-(3-hydroxy-4-(4-hydroxypiperidin-1-yl)-3-methyl-4-oxobutyl)-3,5,6-trimethylcyclohexa-2,5-diene-1,4-dione; -   (S)-2-(3-hydroxy-4-(4-hydroxypiperidin-1-yl)-3-methyl-4-oxobutyl)-3,5,6-trimethylcyclohexa-2,5-diene-1,4-dione; -   N-(2-fluorophenethyl)-2-hydroxy-2-methyl-4-(2,4,5-trimethyl-3,6-dioxocyclohexa-1,4-dienyl)butanamide; -   N-(3-fluorophenethyl)-2-hydroxy-2-methyl-4-(2,4,5-trimethyl-3,6-dioxocyclohexa-1,4-dienyl)butanamide; -   N-(4-fluorophenethyl)-2-hydroxy-2-methyl-4-(2,4,5-trimethyl-3,6-dioxocyclohexa-1,4-dienyl)butanamide; -   N-(3-chlorophenethyl)-2-hydroxy-2-methyl-4-(2,4,5-trimethyl-3,6-dioxocyclohexa-1,4-dienyl)butanamide; -   N-(4-chlorophenethyl)-2-hydroxy-2-methyl-4-(2,4,5-trimethyl-3,6-dioxocyclohexa-1,4-dienyl)butanamide; -   N-(4-fluorophenyl)-2-hydroxy-2-methyl-4-(2,4,5-trimethyl-3,6-dioxocyclohexa-1,4-dienyl)butanamide; -   N-(4-chlorophenyl)-2-hydroxy-2-methyl-4-(2,4,5-trimethyl-3,6-dioxocyclohexa-1,4-dienyl)butanamide; -   N-(2-fluorobenzyl)-2-hydroxy-2-methyl-4-(2,4,5-trimethyl-3,6-dioxocyclohexa-1,4-dienyl)butanamide; -   N-(3-fluorobenzyl)-2-hydroxy-2-methyl-4-(2,4,5-trimethyl-3,6-dioxocyclohexa-1,4-dienyl)butanamide; -   N-(4-fluorobenzyl)-2-hydroxy-2-methyl-4-(2,4,5-trimethyl-3,6-dioxocyclohexa-1,4-dienyl)butanamide; -   N-(2-chlorobenzyl)-2-hydroxy-2-methyl-4-(2,4,5-trimethyl-3,6-dioxocyclohexa-1,4-dienyl)butanamide; -   N-(3-chlorobenzyl)-2-hydroxy-2-methyl-4-(2,4,5-trimethyl-3,6-dioxocyclohexa-1,4-dienyl)butanamide; -   N-(4-chlorobenzyl)-2-hydroxy-2-methyl-4-(2,4,5-trimethyl-3,6-dioxocyclohexa-1,4-dienyl)butanamide;     exhibited protection against LHON with an EC₅₀ of less than about     100 nM

Example D Screening Compounds of the Invention in Fibroblasts from Parkinson's Disease Patients

Compounds of the invention were screened as described in Example A, but substituting FRDA cells with Parkinson's Disease (PD) cells obtained from the Coriell Cell Repositories (Camden, N.J.; repository number AG20439). The compounds were tested for their ability to rescue human dermal fibroblasts from Parkinson's Disease patients from oxidative stress.

Certain compounds of the present invention such as:

-   2-hydroxy-N-isopropyl-2-methyl-4-(2,4,5-trimethyl-3,6-dioxocyclohexa-1,4-dienyl)butanamide; -   2-hydroxy-N-(2-hydroxyethyl)-2-methyl-4-(2,4,5-trimethyl-3,6-dioxocyclohexa-1,4-dienyl)butanamide; -   2-hydroxy-N-(5-hydroxypentyl)-2-methyl-4-(2,4,5-trimethyl-3,6-dioxocyclohexa-1,4-dienyl)butanamide; -   (R)-2-hydroxy-N-(2-hydroxyethyl)-2-methyl-4-(2,4,5-trimethyl-3,6-dioxocyclohexa-1,4-dienyl)butanamide; -   (S)-2-hydroxy-N-(2-hydroxyethyl)-2-methyl-4-(2,4,5-trimethyl-3,6-dioxocyclohexa-1,4-dienyl)butanamide; -   N-(3-(1H-imidazol-1-yl)propyl)-2-hydroxy-2-methyl-4-(2,4,5-trimethyl-3,6-dioxocyclohexa-1,4-dienyl)butanamide; -   2-hydroxy-N-(2-(2-hydroxyethoxy)ethyl)-2-methyl-4-(2,4,5-trimethyl-3,6-dioxocyclohexa-1,4-dienyl)butanamide; -   2-(4-(4-benzylpiperazin-1-yl)-3-hydroxy-3-methyl-4-oxobutyl)-3,5,6-trimethylcyclohexa-2,5-diene-1,4-dione; -   N-(2-(dimethylamino)ethyl)-2-hydroxy-2-methyl-4-(2,4,5-trimethyl-3,6-dioxocyclohexa-1,4-dienyl)butanamide; -   2-hydroxy-N-(4-hydroxyphenethyl)-2-methyl-4-(2,4,5-trimethyl-3,6-dioxocyclohexa-1,4-dienyl)butanamide; -   N-(3-(dimethylamino)propyl)-2-hydroxy-2-methyl-4-(2,4,5-trimethyl-3,6-dioxocyclohexa-1,4-dienyl)butanamide;     exhibited protection against PD with an EC₅₀ of less than about 100     nM

Example E Screening Compounds of the Invention in Fibroblasts from CoQ10 Deficient Patients

Compounds of the invention were tested using a screen similar to the one described in Example A, but substituting FRDA cells with cells obtained from CoQ10 deficient patients harboring a CoQ2 mutation. The compounds were tested for their ability to rescue human dermal fibroblasts from CoQ10 deficient patients from oxidative stress.

-   2-hydroxy-N-(2-hydroxyethyl)-2-methyl-4-(2,4,5-trimethyl-3,6-dioxocyclohexa-1,4-dienyl)butanamide; -   N-hexyl-2-hydroxy-2-methyl-4-(2,4,5-trimethyl-3,6-dioxocyclohexa-1,4-dienyl)butanamide; -   2-hydroxy-2-methyl-4-(2,4,5-trimethyl-3,6-dioxocyclohexa-1,4-dienyl)butanamide; -   N-(2-(dimethylamino)ethyl)-2-hydroxy-2-methyl-4-(2,4,5-trimethyl-3,6-dioxocyclohexa-1,4-dienyl)butanamide; -   2-hydroxy-2-methyl-N-(pyridin-3-ylmethyl)-4-(2,4,5-trimethyl-3,6-dioxocyclohexa-1,4-dienyl)butanamide; -   2-(4-(4-acetylpiperazin-1-yl)-3-hydroxy-3-methyl-4-oxobutyl)-3,5,6-trimethylcyclohexa-2,5-diene-1,4-dione; -   2-(3-hydroxy-3-methyl-4-oxo-4-(piperazin-1-yl)butyl)-3,5,6-trimethylcyclohexa-2,5-diene-1,4-dione; -   tert-butyl     4-(2-hydroxy-2-methyl-4-(2,4,5-trimethyl-3,6-dioxocyclohexa-1,4-dienyl)butanoyl)piperazine-1-carboxylate; -   (S)-2-hydroxy-2-methyl-4-(2,4,5-trimethyl-3,6-dioxocyclohexa-1,4-dienyl)butanamide; -   N-(2-chlorophenethyl)-2-hydroxy-2-methyl-4-(2,4,5-trimethyl-3,6-dioxocyclohexa-1,4-dienyl)butanamide; -   N-(4-fluorophenyl)-2-hydroxy-2-methyl-4-(2,4,5-trimethyl-3,6-dioxocyclohexa-1,4-dienyl)butanamide; -   N-(4-chlorophenyl)-2-hydroxy-2-methyl-4-(2,4,5-trimethyl-3,6-dioxocyclohexa-1,4-dienyl)butanamide;     exhibited protection against CoQ10 deficiency with an EC₅₀ of less     than about 100 nM.

Example F Screening Compounds of the Invention in Human Dermal Fibroblasts from Autistic Patients

A screen was performed to identify compounds effective for the amelioration of ASD. Test samples, and solvent controls were tested for their ability to rescue ASD fibroblasts stressed by addition of L-buthionine-(S,R)-sulfoximine (BSO).

MEM (a medium enriched in amino acids and vitamins, catalog no. Gibco 11965) and Fetal Calf Serum were obtained from Invitrogen. Basic fibroblast growth factor and epidermal growth factor were purchased from PeproTech. Penicillin-streptomycin-glutamine mix, L-buthionine (S,R)-sulfoximine, and insulin from bovine pancreas were purchased from Sigma. Calcein AM was purchased from Molecular Probes. Cell culture medium (ATP) was made by combining 75 ml Fetal Calf Serum, 100 U/ml penicillin, 100 μg/ml streptomycin, 2 mM glutamine, 10 ng/ml EGF, and 10 ng/ml bFGF; MEM EBS was added to make the volume up to 500 ml. A 10 mM BSO solution was prepared by dissolving 444 mg BSO in 200 ml of medium with subsequent filter-sterilization. During the course of the experiments, this solution was stored at +4° C. The cells obtained from Dr. J. M. Shoffner , Medical Neurogenetics, Atlanta, Ga. were grown in 10 cm tissue culture plates. Every week, they were split at a 1:3 ratio. The samples were supplied in 1.5 ml glass vials. The compounds were diluted with DMSO, ethanol or PBS to result in a 5 mM stock solution. Once dissolved, they were stored at −20° C.

The samples were screened according to the following protocol: A culture with ASD fibroblasts was started from a 1 ml vial with approximately 500,000 cells stored in liquid nitrogen. Cells were propagated in 10 cm cell culture dishes by splitting every week in a ratio of 1:3 until nine plates were available. Once confluent, fibroblasts were harvested. For 54 micro titer plates (96 well-MTP) a total of 14.3 million cells (passage eight) were re-suspended in 480 ml medium, corresponding to 100 medium with 3,000 cells/well. The remaining cells were distributed in 10 cm cell culture plates (500,000 cells/plate) for propagation. The plates were incubated overnight at 37° C. in an atmosphere with 95% humidity and 5% CO₂ to allow attachment of the cells to the culture plate.

MTP medium (243 μl) was added to a well of the microtiter plate. The test compounds were unfrozen, and 7.5 μl of a 5 mM stock solution was dissolved in the well containing 243 μl medium, resulting in a 150 μM master solution. Serial dilutions from the master solution were made. The period between the single dilution steps was kept as short as possible (generally less than 1 second).

Plates were kept overnight in the cell culture incubator. The next day, 10 of a 10 mM BSO solution were added to the wells, resulting in a 1 mM final BSO concentration. Forty-eight hours later, three plates were examined under a phase-contrast microscope to verify that the cells in the 0% control (wells E1-H1) were clearly dead. The medium from all plates was discarded, and the remaining liquid was removed by gently tapping the plate inversed onto a paper towel.

100 μl of PBS containing 1.2 μM Calcein AM were then added to each well. The plates were incubated for 50-70 minutes at room temperature. After that time the PBS was discarded, the plate gently tapped on a paper towel and fluorescence (excitation/emission wavelengths of 485 nm and 525 nm, respectively) was read on a Gemini fluorescence reader. Data was imported into Microsoft Excel (EXCEL is a registered trademark of Microsoft Corporation for a spreadsheet program) and used to calculate the EC₅₀ concentration for each compound.

The compounds were tested three times, i.e., the experiment was performed three times, the passage number of the cells increasing by one with every repetition.

The solvents (DMSO, ethanol, PBS) neither had a detrimental effect on the viability of non-BSO treated cells nor did they have a beneficial influence on BSO-treated fibroblasts even at the highest concentration tested (1%). None of the compounds showed auto-fluorescence. The viability of non-BSO treated fibroblasts was set as 100%, and the viability of the BSO- and compound-treated cells was calculated as relative to this value.

Compounds of the present invention are considered to be active if they exhibit protection against ASD with an EC₅₀ of less than 300 nM. A compound of the invention was tested using the protocol above, and showed 50 nM activity.

The disclosures of all publications, patents, patent applications and published patent applications referred to herein by an identifying citation are hereby incorporated herein by reference in their entirety.

Although the foregoing invention has been described in some detail by way of illustration and example for purposes of clarity of understanding, it is apparent to those skilled in the art that certain minor changes and modifications will be practiced. Therefore, the description and examples should not be construed as limiting the scope of the invention. 

1. (canceled)
 2. A method of treating or suppressing a mitochondrial disorder, comprising administering to a subject a therapeutically effective amount or effective amount of one or more compounds of Formula I:

where R is selected from the group consisting of:

where the * indicates the point of attachment of R to the remainder of the molecule; R¹, R², and R³ are independently selected from hydrogen and C₁-C₆-alkyl; R⁴ is C₁-C₆-alkyl; R⁵ and R⁶ are independently selected from hydrogen, hydroxy, alkoxy, C₁-C₄₀-alkyl, C₁-C₄₀-alkenyl, C₁-C₄₀-alkynyl, and aryl; where the alkyl, alkenyl, alkynyl, or aryl groups may optionally be substituted with OR¹⁰, —S(O)₀₋₂R¹⁰, —CN, —F, —Cl, —Br, —I, —NR¹⁰R^(10′), oxo, C₃-C₆-cycloalkyl, aryl, aryl-C₁-C₆-alkyl, heteroaryl, heterocyclyl, —C(O)—R¹¹, —C(O)—C₀-C₆-alkyl-aryl, —C(O)—O—R¹¹, —C(O)—O—C₀-C₆-alkyl-aryl, —C(O)—N—R¹¹R¹¹, —C(O)—N—C₀-C₆-alkyl-aryl, —N—C(O)—R¹¹, —N—C(O)—C₀-C₆-alkyl-aryl; where the aryl, heteroaryl and heterocyclyl ring substituents may be further substituted with C₁-C₆-alkyl, C₁-C₆-haloalkyl, oxo, hydroxy, C₁-C₆-alkoxy, —C(O)—C₁-C₆-alkyl and —C(O)—O—C₁-C₆-alkyl; and where one of the carbons of the alkyl, alkenyl, or alkynyl groups may be substituted with a heteroatom selected from —O—, —N— or —S—; R¹⁰ and R^(10′) are independently selected from the group consisting of hydrogen, C₁-C₆-alkyl, C₁-C₆-haloalkyl, aryl, aryl-C₁-C₆-alkyl, heteroaryl, heterocyclyl, —C(O)—H, —C(O)—C₁-C₆-alkyl, —C(O)-aryl and —C(O)—C₁-C₆-alkyl-aryl; R¹¹ and R^(11′) are selected from hydrogen and C₁-C₆-alkyl; and M and M′ are independently selected from hydrogen, —C(O)—R¹², —C(O)—C₁-C₆-alkenyl, —C(O)—C₁-C₆-alkynyl, —C(O)-aryl; —C(O)-heteroaryl, —C(O)O—R¹², —C(O)NR¹²R¹², —SO₂OR¹², —SO₂—C₁-C₆-alkyl, —SO₂-haloC₁-C₆-alkyl; —SO₂-aryl, —SO₂—NR¹²R¹², P(O)(OR¹²)(OR¹²), and C-linked mono or di-peptide, where R¹² is hydrogen or C₁-C₆-alkyl optionally substituted with —OH, —NH₂—NH(C₁-C₄alkyl), —N(C₁-C₄alkyl)₂—C(O)—OH, —C(O)—O—C₁-C₄-alkyl or halogen; or a salt, a stereoisomer, or a mixture of stereoisomers thereof. 3-14. (canceled)
 15. A method of treating or suppressing a mitochondrial disorder, by administering a therapeutically effective amount of one or more compounds of Formula Ia:

where R¹, R², and R³ are independently selected from hydrogen and C₁-C₆-alkyl; R⁴ is C₁-C₆-alkyl; R⁵ and R⁶ are independently selected from hydrogen, hydroxy, alkoxy, C₁-C₄₀-alkyl, C₁-C₄₀-alkenyl, C₁-C₄₀-alkynyl, and aryl; where the alkyl, alkenyl, alkynyl, or aryl groups may optionally be substituted with —OR¹⁰, —S(O)₀₋₂R¹⁰, —CN, —F, —Cl, —Br, —I, —NR¹⁰R^(10′), oxo, C₃-C₆-cycloalkyl, aryl, aryl-C₁-C₆-alkyl, heteroaryl, heterocyclyl, —C(O)—R¹¹, —C(O)—C₀-C₆-alkyl-aryl, —C(O)—O—R¹¹, —C(O)—O—C₀-C₆-alkyl-aryl, —C(O)—N—R¹¹R¹¹, —C(O)—N—C₀-C₆-alkyl-aryl, —N—C(O)—R¹¹, —N—C(O)—C₀-C₆-alkyl-aryl; where the aryl, heteroaryl and heterocyclyl ring substituents may be further substituted with C₁-C₆-alkyl, C₁-C₆-haloalkyl, oxo, hydroxy, C₁-C₆-alkoxy, —C(O)—C₁-C₆-alkyl and —C(O)—O—C₁-C₆-alkyl; and where one of the carbons of the alkyl, alkenyl, or alkynyl groups may be substituted with a heteroatom selected from O, N or S; R¹⁰ and R^(10′) are independently selected from the group consisting of hydrogen, C₁-C₆-alkyl, C₁-C₆-haloalkyl, aryl, aryl-C₁-C₆-alkyl, heteroaryl, heterocyclyl, —C(O)—H, —C(O)—C₁-C₆-alkyl, —C(O)-aryl and —C(O)—C₁-C₆-alkyl-aryl; and R¹¹ and R^(11′) are selected from hydrogen and C₁-C₆-alkyl; or a salt, a stereoisomer, or a mixture of stereoisomers thereof.
 16. The method of claim 15, comprising treating or suppressing the mitochondrial disorder, where the mitochondrial disorder is selected from the group consisting of inherited mitochondrial diseases; Myoclonic Epilepsy with Ragged Red Fibers (MERRF); Mitochondrial Myopathy, Encephalopathy, Lactacidosis, and Stroke (MELAS); Leber's Hereditary Optic Neuropathy (LHON); Leigh Disease; Kearns-Sayre Syndrome (KSS); Friedreich's Ataxia (FA); other myopathies; cardiomyopathy; encephalomyopathy; renal tubular acidosis; neurodegenerative diseases; Parkinson's disease; Alzheimer's disease; amyotrophic lateral sclerosis (ALS); motor neuron diseases; other neurological diseases; epilepsy; genetic diseases; Huntington's Disease; mood disorders; schizophrenia; bipolar disorder; age-associated diseases; cerebral vascular accidents, macular degeneration; diabetes; and cancer.
 17. The method of claim 15, comprising treating or suppressing the mitochondrial disorder where the mitochondrial disease is selected from group consisting of inherited mitochondrial diseases; Myoclonic Epilepsy with Ragged Red Fibers (MERRF); Mitochondrial Myopathy, Encephalopathy, Lactacidosis, and Stroke (MELAS); Leber's Hereditary Optic Neuropathy (LHON); Leigh Disease; Kearns-Sayre Syndrome (KSS); and Friedreich's Ataxia (FA).
 18. A method according to claim 15 of treating a subject suffering from a pervasive development disorder, comprising administering a therapeutically effective amount of a compound of Formula Ia to a subject suffering from a disorder selected from Autistic Disorder, Asperger's Disorder, Childhood Disintegrative Disorder (CDD), Rett's Disorder, and Pervasive Developmental Disorder-Not Otherwise Specified (PDD-NOS)
 19. The method of claim 18, wherein the pervasive development disorder is Autistic Disorder.
 20. The method of claim 15, comprising treating or suppressing the mitochondrial disorder where the disease is Huntington's disease.
 21. The method of claim 15, comprising treating or suppressing the mitochondrial disorder where the disease is Parkinson's disease.
 22. The method of claim 15, comprising treating or suppressing the mitochondrial disorder with a compound selected from: 2-hydroxy-N-isopropyl-2-methyl-4-(2,4,5-trimethyl-3,6-dioxocyclohexa-1,4-dienyl)butanamide; 2-hydroxy-N-(2-hydroxyethyl)-2-methyl-4-(2,4,5-trimethyl-3,6-dioxocyclohexa-1,4-dienyl)butanamide; N-hexyl-2-hydroxy-2-methyl-4-(2,4,5-trimethyl-3,6-dioxocyclohexa-1,4-dienyl)butanamide; N-tert-butyl-2-hydroxy-2-methyl-4-(2,4,5-trimethyl-3,6-dioxocyclohexa-1,4-dienyl)butanamide; 2-hydroxy-N,N,2-trimethyl-4-(2,4,5-trimethyl-3,6-dioxocyclohexa-1,4-dienyl)butanamide; N-ethyl-2-hydroxy-2-methyl-4-(2,4,5-trimethyl-3,6-dioxocyclohexa-1,4-dienyl)butanamide; N-benzyl-2-hydroxy-2-methyl-4-(2,4,5-trimethyl-3,6-dioxocyclohexa-1,4-dienyl) butanamide; 2-hydroxy-2-methyl-N-propyl-4-(2,4,5-trimethyl-3,6-dioxocyclohexa-1,4-dienyl)butanamide; N-(cyclopropylmethyl)-2-hydroxy-2-methyl-4-(2,4,5-trimethyl-3,6-dioxocyclohexa-1,4-dienyl)butanamide; 2-hydroxy-2-methyl-N-phenethyl-4-(2,4,5-trimethyl-3,6-dioxocyclohexa-1,4-dienyl)butanamide; 2-hydroxy-N-(3-hydroxypropyl)-2-methyl-4-(2,4,5-trimethyl-3,6-dioxocyclohexa-1,4-dienyl)butanamide; 2-hydroxy-N-isopentyl-2-methyl-4-(2,4,5-trimethyl-3,6-dioxocyclohexa-1,4-dienyl)butanamide; N-cyclopropyl-2-hydroxy-2-methyl-4-(2,4,5-trimethyl-3,6-dioxocyclohexa-1,4-dienyl)butanamide; 2-hydroxy-N-isobutyl-2-methyl-4-(2,4,5-trimethyl-3,6-dioxocyclohexa-1,4-dienyl)butanamide; N-ethyl-2-hydroxy-N,2-dimethyl-4-(2,4,5-trimethyl-3,6-dioxocyclohexa-1,4-dienyl)butanamide; 2-hydroxy-2-methyl-4-(2,4,5-trimethyl-3,6-dioxocyclohexa-1,4-dienyl)butanamide; 2-hydroxy-N-(4-hydroxybutyl)-2-methyl-4-(2,4,5-trimethyl-3,6-dioxocyclohexa-1,4-dienyl)butanamide; 2-hydroxy-N-(5-hydroxypentyl)-2-methyl-4-(2,4,5-trimethyl-3,6-dioxocyclohexa-1,4-dienyl)butanamide; 2-hydroxy-N-(2-methoxyethyl)-2-methyl-4-(2,4,5-trimethyl-3,6-dioxocyclohexa-1,4-dienyl)butanamide; 2-hydroxy-N-(1-hydroxypropan-2-yl)-2-methyl-4-(2,4,5-trimethyl-3,6-dioxocyclohexa-1,4-dienyl)butanamide; (R)-2-hydroxy-N-(2-hydroxyethyl)-2-methyl-4-(2,4,5-trimethyl-3,6-dioxocyclohexa-1,4-dienyl)butanamide; (S)-2-hydroxy-N-(2-hydroxyethyl)-2-methyl-4-(2,4,5-trimethyl-3,6-dioxocyclohexa-1,4-dienyl)butanamide; methyl 2-(2-hydroxy-2-methyl-4-(2,4,5-trimethyl-3,6-dioxocyclohexa-1,4-dienyl)butanamido)acetate; N-(3-(1H-imidazol-1-yl)propyl)-2-hydroxy-2-methyl-4-(2,4,5-trimethyl-3,6-dioxocyclohexa-1,4-dienyl)butanamide; 2-hydroxy-N-(2-(2-hydroxyethoxy)ethyl)-2-methyl-4-(2,4,5-trimethyl-3,6-dioxocyclohexa-1,4-dienyl)butanamide; 2-hydroxy-2-methyl-N-(pyridin-2-ylmethyl)-4-(2,4,5-trimethyl-3,6-dioxocyclohexa-1,4-dienyl)butanamide; 2-hydroxy-2-methyl-N-(2-(pyridin-2-yl)ethyl)-4-(2,4,5-trimethyl-3,6-dioxocyclohexa-1,4-dienyl)butanamide; 2-hydroxy-2-methyl-N-(3-(2-oxopyrrolidin-1-yl)propyl)-4-(2,4,5-trimethyl-3,6-dioxocyclohexa-1,4-dienyl)butanamide; 2-hydroxy-N-(2-hydroxypropyl)-2-methyl-4-(2,4,5-trimethyl-3,6-dioxocyclohexa-1,4-dienyl)butanamide; 2-hydroxy-N-(6-hydroxyhexyl)-2-methyl-4-(2,4,5-trimethyl-3,6-dioxocyclohexa-1,4-dienyl)butanamide; 2-hydroxy-2-methyl-N-((tetrahydrofuran-2-yl)methyl)-4-(2,4,5-trimethyl-3,6-dioxocyclohexa-1,4-dienyl)butanamide; 2-hydroxy-2-methyl-N-(3-morpholinopropyl)-4-(2,4,5-trimethyl-3,6-dioxocyclohexa-1,4-dienyl)butanamide; 2-hydroxy-N-methoxy-N,2-dimethyl-4-(2,4,5-trimethyl-3,6-dioxocyclohexa-1,4-dienyl)butanamide; 2-hydroxy-N,N-bis(2-hydroxyethyl)-2-methyl-4-(2,4,5-trimethyl-3,6-dioxocyclohexa-1,4-dienyl)butanamide; N-(2-(dimethylamino)ethyl)-2-hydroxy-2-methyl-4-(2,4,5-trimethyl-3,6-dioxocyclohexa-1,4-dienyl)butanamide; 2-hydroxy-N-(4-hydroxyphenethyl)-2-methyl-4-(2,4,5-trimethyl-3,6-dioxocyclohexa-1,4-dienyl)butanamide; N-(3-(dimethylamino)propyl)-2-hydroxy-2-methyl-4-(2,4,5-trimethyl-3,6-dioxocyclohexa-1,4-dienyl)butanamide; N-butyl-2-hydroxy-2-methyl-4-(2,4,5-trimethyl-3,6-dioxocyclohexa-1,4-dienyl)butanamide; 2-hydroxy-N-(2-hydroxyethyl)-N,2-dimethyl-4-(2,4,5-trimethyl-3,6-dioxocyclohexa-1,4-dienyl)butanamide; N,N-diethyl-2-hydroxy-2-methyl-4-(2,4,5-trimethyl-3,6-dioxocyclohexa-1,4-dienyl)butanamide; tert-butyl 2-(2-hydroxy-2-methyl-4-(2,4,5-trimethyl-3,6-dioxocyclohexa-1,4-dienyl)butanamido)ethylcarbamate; 2-hydroxy-2-methyl-N-(pyridin-4-ylmethyl)-4-(2,4,5-trimethyl-3,6-dioxocyclohexa-1,4-dienyl)butanamide; 2-hydroxy-2-methyl-N-(pyridin-3-ylmethyl)-4-(2,4,5-trimethyl-3,6-dioxocyclohexa-1,4-dienyl)butanamide; 2-hydroxy-2-methyl-N-(3-(methylsulfonyl)propyl)-4-(2,4,5-trimethyl-3,6-dioxocyclohexa-1,4-dienyl)butanamide; 2-(2-hydroxy-2-methyl-4-(2,4,5-trimethyl-3,6-dioxocyclohexa-1,4-dienyl)butanamido)acetic acid; (R)-2-hydroxy-2-methyl-4-(2,4,5-trimethyl-3,6-dioxocyclohexa-1,4-dienyl)butanamide; (S)-2-hydroxy-2-methyl-4-(2,4,5-trimethyl-3,6-dioxocyclohexa-1,4-dienyl)butanamide; N-(2-fluorophenethyl)-2-hydroxy-2-methyl-4-(2,4,5-trimethyl-3,6-dioxocyclohexa-1,4-dienyl)butanamide; N-(3-fluorophenethyl)-2-hydroxy-2-methyl-4-(2,4,5-trimethyl-3,6-dioxocyclohexa-1,4-dienyl)butanamide; N-(4-fluorophenethyl)-2-hydroxy-2-methyl-4-(2,4,5-trimethyl-3,6-dioxocyclohexa-1,4-dienyl)butanamide; N-(2-chlorophenethyl)-2-hydroxy-2-methyl-4-(2,4,5-trimethyl-3,6-dioxocyclohexa-1,4-dienyl)butanamide; N-(3-chlorophenethyl)-2-hydroxy-2-methyl-4-(2,4,5-trimethyl-3,6-dioxocyclohexa-1,4-dienyl)butanamide; N-(4-chlorophenethyl)-2-hydroxy-2-methyl-4-(2,4,5-trimethyl-3,6-dioxocyclohexa-1,4-dienyl)butanamide; 2-hydroxy-N-(4-methoxyphenyl)-2-methyl-4-(2,4,5-trimethyl-3,6-dioxocyclohexa-1,4-dienyl)butanamide; N-(4-fluorophenyl)-2-hydroxy-2-methyl-4-(2,4,5-trimethyl-3,6-dioxocyclohexa-1,4-dienyl)butanamide; N-(4-chlorophenyl)-2-hydroxy-2-methyl-4-(2,4,5-trimethyl-3,6-dioxocyclohexa-1,4-dienyl)butanamide; N-(2-fluorobenzyl)-2-hydroxy-2-methyl-4-(2,4,5-trimethyl-3,6-dioxocyclohexa-1,4-dienyl)butanamide; N-(3-fluorobenzyl)-2-hydroxy-2-methyl-4-(2,4,5-trimethyl-3,6-dioxocyclohexa-1,4-dienyl)butanamide; N-(4-fluorobenzyl)-2-hydroxy-2-methyl-4-(2,4,5-trimethyl-3,6-dioxocyclohexa-1,4-dienyl)butanamide; N-(2-chlorobenzyl)-2-hydroxy-2-methyl-4-(2,4,5-trimethyl-3,6-dioxocyclohexa-1,4-dienyl)butanamide; N-(3-chlorobenzyl)-2-hydroxy-2-methyl-4-(2,4,5-trimethyl-3,6-dioxocyclohexa-1,4-dienyl)butanamide; N-(4-chlorobenzyl)-2-hydroxy-2-methyl-4-(2,4,5-trimethyl-3,6-dioxocyclohexa-1,4-dienyl)butanamide; or a salt, a stereoisomer, or a mixture of stereoisomers thereof. 23-25. (canceled)
 26. A method of treating or suppressing a mitochondrial disorder, comprising administering to a subject a therapeutically effective amount or effective amount of one or more compounds of Formula Ib:

R¹, R², and R³ are independently selected from hydrogen and C₁-C₆-alkyl; R⁴ is C₁-C₆-alkyl; R⁵ and R⁶ are independently selected from hydrogen, hydroxy, alkoxy, C₁-C₄₀-alkyl, C₁-C₄₀-alkenyl, C₁-C₄₀-alkynyl, and aryl; where the alkyl, alkenyl, alkynyl, or aryl groups may optionally be substituted with —OR¹⁰, —S(O)₀₋₂R¹⁰, —CN, —F, —Cl, —Br, —I, —NR¹⁰R^(10′), oxo, C₃-C₆-cycloalkyl, aryl, aryl-C₁-C₆-alkyl, heteroaryl, heterocyclyl, —C(O)—R¹¹, —C(O)—C₀-C₆-alkyl-aryl, —C(O)—O—R¹¹, —C(O)—O—C₀-C₆-alkyl-aryl, —C(O)—N—R¹¹R¹¹, —C(O)—N—C₀-C₆-alkyl-aryl, —N—C(O)—R¹¹, —N—C(O)—C₀-C₆-alkyl-aryl; where the aryl, heteroaryl and heterocyclyl ring substituents may be further substituted with C₁-C₆-alkyl, C₁-C₆-haloalkyl, oxo, hydroxy, C₁-C₆-alkoxy, —C(O)—C₁-C₆-alkyl and —C(O)—O—C₁-C₆-alkyl; and where one of the carbons of the alkyl, alkenyl, or alkynyl groups may be substituted with a heteroatom selected from O, N or S; R¹⁰ and R^(10′) are independently selected from the group consisting of hydrogen, C₁-C₆-alkyl, C₁-C₆-haloalkyl, aryl, aryl-C₁-C₆-alkyl, heteroaryl, heterocyclyl, —C(O)—H, —C(O)—C₁-C₆-alkyl, —C(O)-aryl and —C(O)—C₁-C₆-alkyl-aryl; or R¹⁰ and R^(10′) together with the atom to which they are attached form an optionally substituted saturated or unsaturated 3-8 membered ring, optionally incorporating 1, 2, or 3 N, O, or S atoms; R¹¹ and R^(11′) are selected from hydrogen and C₁-C₆-alkyl; and M and M′ are independently selected from hydrogen, —C(O)—R¹², —C(O)—C₁-C₆-alkenyl, —C(O)—C₁-C₆-alkynyl, —C(O)-aryl; —C(O)-heteroaryl, —C(O)O—R¹², —C(O)NR¹²R¹², —SO₂OR¹², —SO₂—C₁-C₆-alkyl, —SO₂-haloC₁-C₆-alkyl; —SO₂-aryl, —SO₂—NR¹²R¹², —P(O)(OR¹²)(OR¹²), and C-linked mono or di-peptide, where R¹² is hydrogen or C₁-C₆-alkyl optionally substituted with —OH, —NH₂, —NH(C₁-C₄alkyl), —N(C₁-C₄alkyl)₂—C(O)—OH, —C(O)—O—C₁-C₄-alkyl or halogen; or a salt, a stereoisomer, or a mixture of stereoisomers thereof.
 27. The method of claim 26, comprising treating or suppressing the mitochondrial disorder, where the mitochondrial disorder is selected from the group consisting of inherited mitochondrial diseases; Myoclonic Epilepsy with Ragged Red Fibers (MERRF); Mitochondrial Myopathy, Encephalopathy, Lactacidosis, and Stroke (MELAS); Leber's Hereditary Optic Neuropathy (LHON); Leigh Disease; Kearns-Sayre Syndrome (KSS); Friedreich's Ataxia (FA); other myopathies; cardiomyopathy; encephalomyopathy; renal tubular acidosis; neurodegenerative diseases; Parkinson's disease; Alzheimer's disease; amyotrophic lateral sclerosis (ALS); motor neuron diseases; other neurological diseases; epilepsy; genetic diseases; Huntington's Disease; mood disorders; schizophrenia; bipolar disorder; age-associated diseases; cerebral vascular accidents, macular degeneration; diabetes; and cancer.
 28. The method of claim 27, comprising treating or suppressing the mitochondrial disorder where the mitochondrial disease is selected from group consisting of inherited mitochondrial diseases; Myoclonic Epilepsy with Ragged Red Fibers (MERRF); Mitochondrial Myopathy, Encephalopathy, Lactacidosis, and Stroke (MELAS); Leber's Hereditary Optic Neuropathy (LHON); Leigh Disease; Kearns-Sayre Syndrome (KSS); and Friedreich's Ataxia (FA).
 29. The method of claim 27, comprising treating or suppressing the mitochondrial disorder where the mitochondrial disorder is selected from the group consisting of Huntington's disease and Parkinson's disease.
 30. (canceled)
 31. The method of claim 26, wherein the subject is suffering from a disorder selected from Autistic Disorder, Asperger's Disorder, Childhood Disintegrative Disorder (CDD), Rett's Disorder, and Pervasive Developmental Disorder-Not Otherwise Specified (PDD-NOS).
 32. The method of treating or suppressing a mitochondrial disorder according to claim 2, comprising administering to a subject in need of such treatment a therapeutically effective amount or effective amount of one or more compounds of Formula I, where R¹, R², R³, and R⁴ are methyl, or a salt, a stereoisomer, or a mixture of stereoisomers thereof.
 33. The method of treating or suppressing a mitochondrial disorder according to claim 2, comprising administering to a subject in need of such treatment a therapeutically effective amount or effective amount of one or more compounds of Formula I where R⁵ is hydrogen and R⁶ is C₁-C₆ alkyl substituted with hydroxy, alkoxy or —C(O)O—C₁-C₆ alkyl, or a salt, a stereoisomer, or a mixture of stereoisomers thereof.
 34. The method of treating or suppressing a mitochondrial disorder according to claim 2, comprising administering to a subject in need of such treatment a therapeutically effective amount or effective amount of one or more compounds of Formula I where R⁵ is hydrogen and R⁶ is independently selected from C₁-C₆ alkyl substituted with —NR¹⁰R^(10′), where R¹⁰ and R^(10′) are independently selected from the group consisting of hydrogen, C₁-C₆-alkyl, C₁-C₆-haloalkyl, aryl, aryl-C₁-C₆-alkyl, heteroaryl, heterocyclyl, —C(O)—H, —C(O)—C₁-C₆-alkyl, —C(O)-aryl and —C(O)—C₁-C₆-alkyl-aryl, or a salt, a stereoisomer, or a mixture of stereoisomers thereof.
 35. The method of treating or suppressing a mitochondrial disorder according to claim 2, comprising administering to a subject in need of such treatment a therapeutically effective amount or effective amount of one or more compounds of Formula I where R⁵ is hydrogen and R⁶ is independently selected from C₁-C₆ alkyl substituted with a heterocyclyl or heteroaryl group, or a salt, a stereoisomer, or a mixture of stereoisomers thereof.
 36. The method of treating or suppressing a mitochondrial disorder according to claim 2, comprising administering to a subject in need of such treatment a therapeutically effective amount or effective amount of one or more compounds of Formula I, where R⁵ and R⁶ are independently hydrogen or C₁-C₆ alkyl optionally substituted with aryl, or a salt, a stereoisomer, or a mixture of stereoisomers thereof.
 37. The method of treating or suppressing a mitochondrial disorder according to claim 2, comprising administering to a subject in need of such treatment a therapeutically effective amount or effective amount of one or more compounds of Formula I, where one of R⁵ and R⁶ is hydrogen and the other group is C₁-C₆ alkyl optionally substituted with aryl, or a salt, a stereoisomer, or a mixture of stereoisomers thereof.
 38. The method of treating or suppressing a mitochondrial disorder according to claim 2, comprising administering to a subject in need of such treatment a therapeutically effective amount or effective amount of one or more compounds of Formula I, where R⁵ and R⁶ are hydrogen, or a salt, a stereoisomer, or a mixture of stereoisomers thereof. 